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.

Example Input: Question: If W is an integer greater than 6, which of the following must be divisible by 3?

 Option A: W(W+1

 Option B: N(N+2

 Option C: N(N+3

 Option D: N(N+4

 Option E: N(N+5
Example Output: Option A

Example Input: Question: If x, y, and z are positive integers such that x is a factor of y and y is a factor of z, which of the following is NOT necessarily an integer?

 Option A: (x + y

 Option B: (y + z

 Option C: yz/x

 Option D: (2y + 3z

 Option E: (xy + z
Example Output: Option A

Example Input: Question: In a group of 20 students, each student is registered for at least one of three classes – History, Math and English. 10 students are registered for History, 10 students are registered for Math, and 15 students are registered for English. If only three students are registered for all three classes, how many students are registered for exactly two classes?

 Option A: 13

 Option B: 10

 Option C: 9

 Option D: 8

 Option E: 7
Example Output:
Option C