Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[EX Q]: Problem: a can finish a work in 60 days, b in 9 days and c in 2 days, b and c start the work but are forced to leave after 3 days. the remaining work was done by a in ?
Options: a. 10 days, b. 25 days, c. 6 days, d. 7 days, e. 8 days
[EX A]: b

[EX Q]: Problem: what is the smallest number by which 2880 must be divided in order to make it into a perfect square ?
Options: a. 3, b. 4, c. 5, d. 6, e. 7
[EX A]: c

[EX Q]: Problem: a woman can do a piece of work in 40 days. man is 25 % more efficient than woman. in how many days a man can do the same piece of work ?
Options: a. 32 days, b. 36 days, c. 38 days, d. 40 days, e. 53 days
[EX A]:
a