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: The greatest common factor of 16 and the positive integer n is 4, and the greatest common factor of n and 45 is 3. Which of the following could be the greatest common factor of n and 210?

Option A: 3

Option B: 14

Option C: 30

Option D: 42

Option E: 70

Ex Output:
Option D

Ex Input:
Question: Patrick purchased 80 pencils and sold them at a loss equal to the selling price of 16 pencils. The cost of 80 pencils is how many times the selling price of 80 pencils?

Option A: 0.75

Option B: 1.2

Option C: 1.8

Option D: 2.4

Option E: 4.25

Ex Output:
Option B

Ex Input:
Question: If 625^(-x) + 25^(-2x) + 5^(-4x) = 10, what is the value of x?

Option A: -4

Option B: -1/4

Option C: 0

Option D: 1/4

Option E: 4

Ex Output:
Option C