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 boat having a length 8 m and breadth 2 m is floating on a lake. the boat sinks by 1 cm when a man gets on it. the mass of the man is :
Options: a. 12 kg, b. 60 kg, c. 72 kg, d. 160 kg, e. none of these
[EX A]: d

[EX Q]: Problem: a walks at 10 kmph and 4 hours after his start, b cycles after him at 20 kmph. how far from the start does b catch up with a ?
Options: a. 100 km, b. 150 km, c. 80 km, d. 120 km, e. 200 km
[EX A]: c

[EX Q]: Problem: a sum fetched a total simple interest of $ 4196.25 at the rate of 9 p. c. p. a. in 5 years. what is the sum ?
Options: a. $ 8829, b. $ 2840, c. $ 6578, d. $ 7782, e. $ 8929
[EX A]:
e