Which statement is false?

a) In a tightly packed binary tree, each level contains about twice as many elements as the previous level.
b) When searching a tightly packed 1,000,000-element binary search tree, a maximum of approximately 20 comparisons need to be made.
c) The level-order traversal of a binary tree visits the nodes of the tree row-by-row starting at the root node level.
d) Searching a binary tree for a value that matches a key value is slow for tightly packed trees.

d) Searching a binary tree for a value that matches a key value is slow for tightly packed trees.