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: anand finishes a work in 7 days, bittu finishes the same job in 8 days and chandu in 6 days. they take turns to finish the work. anand on the first day, bittu on the second and chandu on the third day and then anand again and so on. on which day will the work get over ?
Options: a. 3 rd, b. 6 th, c. 9 th, d. 7 th, e. 8 th
[EX A]: d

[EX Q]: Problem: ages of two persons differ by 20 years. if 6 year ago, the elder one be 3 times as old the younger one, find their present age
Options: a. 12,28, b. 14,30, c. 16,36, d. 18,34, e. 19,34
[EX A]: c

[EX Q]: Problem: a boat having a length 3 m and breadth 2 m is floating on a lake. the boat sinks by 2 cm when a man gets on it. the mass of man is
Options: a. 12 kg, b. 60 kg, c. 72 kg, d. 120 kg, e. none
[EX A]:
d