a) For each of the following problems, propose the key "action/operation you would use to determine the time complexity (short answers are fine here). a. Find the number of occurrences of the character 'e' in a strings of characters. b. Add two nx n matrices A and B c. Copy a string of characters A onto another string B. d. Eliminate (remove) all numbers less than 100 from a list of numbers. e. Traverse (to display e.g.,) a binary tree (represented as a linked structure where each node contains pointers to its left and right children)