Question 7875 – Data-Structures

Let G be a simple undirected graph. Let T_D be a depth first search tree of G. Let T_B be a breadth first search tree of G. Consider the following statements.
(I) No edge of G is a cross edge with respect to T_D.(A cross edge in G is between two nodes neither of which is an ancestor of the other in T_D.)
(II) For every edge (u,v) of G, if u is at depth i and v is at depth j in T_B, then ∣i−j∣ = 1.
Which of the statements above must necessarily be true?

Correct Answer: A