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