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: In a certain school, the ratio of boys to girls is 5 to 13. If there are 160 more girls than boys, how many boys are there?

Option A: 100

Option B: 36

Option C: 45

Option D: 72

Option E: 117

Ex Output:
Option A

Ex Input:
Question: A man can do a piece of work in 5 days, but with the help of his son he can do it in 3 days. In what time can the son do it alone ?

Option A: 13/2

Option B: 19/2

Option C: 21/2

Option D: 15/2

Option E: None

Ex Output:
Option C

Ex Input:
Question: On Monday Joshua sold 90 phones, Rob sold 30% more phones than Joshua, Prerna sold 11 more phones than Rob, and Declan sold 3/4 of what Prerna sold. How many phones did Declan sell?

Option A: 111

Option B: 75

Option C: 29

Option D: 128

Option E: 96

Ex Output:
Option E