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 Input:
Problem: what is the least number of squares tiles required to pave the floor of a room 15.17 m long and 9.02 m broad ?
Options: ['a. 814', 'b. 266', 'c. 287', 'd. 999', 'e. 661']

Ex Output:
a

Ex Input:
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 Output:
d

Ex Input:
Problem: if n = 10 ^ 100 and n ^ n = 10 k what is the value of k ?
Options: a. 200, b. 10 ^ 100, c. 10 ^ 102, d. 100 ^ 100, e. 1000 ^ 10

Ex Output:
c