Solution :
C) is correct
For an k-ary tree where each node has k children or no children, following relation holds L = (k-1)*n + 1 Where L is the number of leaf nodes and n is the number of internal nodes. Let us see following for example o
/ | \
o o o
/|\ /|\
o o o o o o
/|\
o o ok = 3
Number of internal nodes n = 4
Number of leaf nodes = (k-1)*n + 1 = (3-1)*4 + 1 = 9