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: if ( x - 10 ) ( y - 5 ) ( z - 2 ) = 1000 then what is the least value of x + y + z ? if x, y, z are all integer no.
Options: a. 7, b. 8, c. 9, d. 10, e. 11

Ex Output:
a


Ex Input:
Problem: if a certain coin is flipped, the probability that the coin will land heads is 1 / 2. if the coin is flipped 6 times, what is the probability that it will land heads up on the first 4 flips but not on the last 2 flips ?
Options: a. 1 / 8, b. 1 / 16, c. 1 / 32, d. 1 / 64, e. 1 / 128

Ex Output:
d


Ex Input:
Problem: laxmi and prasanna set on a journey. laxmi moves northwards at a speed of 20 kmph and prasanna moves southward at a speed of 30 kmph. how far will be prasanna from laxmi after 60 minutes ?
Options: a. 11, b. 50, c. 28, d. 27, e. 18

Ex Output:

b