→ In two-way communication, wherever a frame is received, the receiver waits and does not send the control frame (acknowledgement or ACK) back to the sender immediately.
→ The receiver waits until its network layer passes in the next data packet. The delayed acknowledgement is then attached to this outgoing data frame.
→ This technique of temporarily delaying the acknowledgement so that it can be hooked with next outgoing data frame is known as piggybacking.

Presentation layer is responsible for
1. Translation, authentication
2. Encryption and Decryption
3. Compression and decompression
But according application layer also can do these responsibilities. So, Optio-C is the correct answer.

→ Bit rate is nothing but number of bits transmitted per second
→ Baud rate is nothing but number of signals units transmitted per unit time.
Given data,
-- Bit rate of a signal=4000 bps
-- Each signal unit carries=4 bits
-- Baud rate=?
Step-1: Baud rate= Bit rate of signal / baud rate
= 4000/4 bps
= 1000 bps
Step-2: Bit rate= Number of bits transmitted per second*number of signals units transmitted per unit time
= 4*1000 bps
= 4000 bps

The VLF and LF bauds use ground propagation for communication.
Propagation methods are 3 types
1. Ground
2. Sky
3. Line of sight

→ Very low frequency or VLF is for radio frequencies (RF) in the range of 3 to 30 kilohertz (kHz), corresponding to wavelengths from 100 to 10 kilometers, respectively.
→ The low-frequency signals travel in all directions from the transmitting antenna.

Step-1: Compute n=p*q
= 13*31
= 403
Step-2: Compute f(n)= (p − 1)(q − 1)
= 12*30
= 360
Step-3: Compute d = e^-1 mod f(n)
Choose an e such that 1 d.e = 1 mod f(n)
e = 1 mod 360
= 361 mod 360
= 721 mod 360
Note: Given d=7
7*e= 721 mod 360
e=103

→ FAN IN of a component A is defined as number of components that can call or pass control to component A.
→ FAN-IN defines “number of modules directly invoking given module”.

→ FAN OUT is the number of classes used by a certain class or the number of methods called by a certain method.
→ FAN OUT defines “Number of modules that are directly controlled by given module.
→ Good software design require High FAN-IN and LOW FAN-OUT

→ Cohesion is a measure of internal strength within a module and relationship of data elements in a module, whereas coupling is a measure of inter dependency among the modules.
→ In the context of modular software design there should be high cohesion and low coupling.

Software Configuration Management is the discipline for systematically controlling
1. The changes due to the evolution of work products as the project proceeds.
2. The changes due to defects(bugs) being found and then fixed.
3. The changes due to requirement changes

Requirements engineering (RE) refers to the process of defining, documenting and maintaining requirements in the engineering design process.
Requirement Analysis Steps:
1. Requirements inception or requirements elicitation: Developers and stakeholders meet, the latter are inquired concerning their needs and wants regarding the software product.
2. Requirements analysis and negotiation: Requirements are identified (including new ones if the development is iterative) and conflicts with stakeholders are solved. Both written and graphical tools (the latter commonly used in the design phase but some find them helpful at this stage, too) are successfully used as aids.
3. System modeling: Some engineering fields (or specific situations) require the product to be completely designed and modeled before its construction or fabrication starts and, therefore, the design phase must be performed in advance.
4. Requirements specification: Requirements are documented in a formal artifact called a Requirements Specification (RS), which will become official only after validation.
5. Requirements validation: Checking that the documented requirements and models are consistent and meet the needs of the stakeholder. Only if the final draft passes the validation process, the RS becomes official.
6. Requirements management: Managing all the activities related to the requirements since inception, supervising as the system is developed and, even until after it is put into use (e. g., changes, extensions, etc.)

→ Alpha test: is conducted at the developer’s site by end-users and conducted in a controlled environment
→ Beta test: is conducted at end-user sites and it is a “live” application of the software in an environment that cannot be controlled by the developer
→ Regression test: Testing is an important strategy for reducing “side effects” when major change is made to the software

Integrity constraint have some rules:
1. Every table have at least one attribute as primary key
2. No prime attribute should ever have null value.
The above example given condition but it is not referring any table. So, it is not referential constraints. Other two are not relevant to this question.
So, Option-A is correct answer.

GO BOTTOM command will directly reach end of the record. Here, total number of records are 30. GO BOTTOM command will reach 30th position.
After SKIP-1, it became 29
After SKIP-2, it became 28
After SKIP-3, it became 27.
In question, they given 3 SKIP operations.