Perspective Projection :
Perspective projection is representing or drawing objects which resemble the real thing.
Perspective projection preserves the straight line.
In perspective projection, objects that are far away appear smaller, and objects that are near appear bigger.
Parallel lines do not remain parallel.
Distance and angles are not preserved.
Parallel Projection :
In this projection drawing objects looks less realistic.
In this projection parallel lines remains parallel.
Angles are not preserved in this projection.
It is good for exact measurements.

Back Face Culling:
→ Back-face culling (an object space algorithm) works on 'solid' objects which you are looking at from the outside. That is, the polygons of the surface of the object completely enclose the object.
→ Back-face culling is not an example of an image-precision visible-surface determination.
→ Back-face culling can very quickly remove unnecessary polygons. Unfortunately there are often times when back-face culling can not be used. For example if you wish to make an open-topped box - the inside and the outside of the box both need to be visible, so either two sets of polygons must be generated, one set facing out and another facing in, or back-face culling must be turned off to draw that object.
1. Back faces: faces of opaque object which are “pointing away” from viewer.
2. Back face culling – remove back faces (supported by OpenGL).
→ TRUE: Z-Buffer is a 16-bit, 32-bit, or 64-bit field associated with each pixel in a frame buffer that can be used to determine the visible surface at each pixel.

In computer graphics, z-buffering, also known as depth buffering, is the management of image depth coordinates in 3D graphics, usually done in hardware, sometimes in software
In a 3d-rendering engine, when an object is projected on the screen, the depth (z-value) of a generated pixel in the projected screen image is stored in a buffer (the z-buffer or depth buffer).
A z-value is the measure of the perpendicular distance from a pixel on the projection plane to its corresponding 3d-coordinate on a polygon in world-space.
Z-buffer requires 2 type of buffers to be filled: Depth buffer and Frame buffer
The amount of memory required by depth buffer in terms of bits is 512 x 512 x 24 = 6291456
The amount of memory required by frame buffer in terms of bits is 512 x 512 x 24 = 6291456
Total memory is required is sum of both depth and frame buffer memories = 6291456 + 6291456 = 12582912 bits which is equivalent to 1.5 MB(1.5x1024x1024x8)

→Projections of lines that are not parallel to the view plane (i.e. lines that are not perpendicular to the view plane normal) appear to meet at some point on the view plane.
→This point is called the vanishing point. A vanishing point corresponds to every set of parallel lines.

The Z-buffer algorithm is a convenient algorithm for rendering images properly according to depth.
To begin with, a buffer containing the closest depth at each pixel location is created parallel to the image buffer. Each location in this depth buffer is initialized to negative infinity.
Since the algorithm processes objects one at a time, the total number of polygons in a picture can be arbitrarily large.

Explanation:
Given file size is 8M bytes= 8*1024**1024*8=83,88,608
From the options,
⦁ 800*600*8=34,80,000
⦁ 1024*768*8=62,91,456
⦁ 1280*1024*8=13,10,720
⦁ 1920*1440*8=22,118,400
From the above , option A and B are less than file size.
From that two , maximum one is option B.

Phong shading is a per-fragment color computation. The vertex shader provides the normal and position data as out variables to the fragment shader. The fragment shader then interpolates these variables and computes the color

Steiner patches are triangular surface patches for which the Cartesian coordinates of points on the patch are defined parametrically by quadratic polynomial functions of two variables. So these surfaces are formed from biquadratic Bezier patches.