You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Ex Input:
Question: 23, 18, 16, 11, 9, 4 ?

 Option A: 3

 Option B: 2

 Option C: 7

 Option D: 5

 Option E: 1

Ex Output:
Option B


Ex Input:
Question: (3x + 1) (2x - 5) = ax^2 + kx + n . What is the value of a - n + k ?

 Option A: 5

 Option B: 8

 Option C: 9

 Option D: 14

 Option E: 11

Ex Output:
Option D


Ex Input:
Question: In the formula V = 1/(3r)^4, if r is halved, then V is multiplied by

 Option A: 64

 Option B: 8

 Option C: 16

 Option D: 1/8

 Option E: 1/64

Ex Output:

Option C