Height will be maximum when the BINARY SEARCH TREE is completely skewed
example for an ASCENDING order sequence of numbers say {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15} hence maximum height will be
14
height will be minimum when tree is maximally packed that is every level is filled completely before moing to next level...
in that case
level 1->1 node
level 2-> 2 node
level 3-> 4 node
level 4-> 8 nodes
so in 4 level total nodes are 1+2+4+8=15
so min height is 3
hence correct answer is
option (B)