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.

Input: Consider Input: Question: If the operation ∆ is defined by a ∆ b = (b - a)^2/a^2 for all numbers a and b, and a ≠ 0, then what is the result when we evaluate this expression: (-5) ∆ (5 ∆ −5) ?

 Option A: 49/9

 Option B: 49/16

 Option C: 81/16

 Option D: 81/25

 Option E: 100/81

Output: Option D


Input: Consider Input: Question: A man ran 20 miles in 2 hours 2 minutes. What was the average speed of the man in miles per hour?

 Option A: 9.72 miles / hour

 Option B: 9.73 miles / hour

 Option C: 9.75 miles / hour

 Option D: 9.78 miles / hour

 Option E: 9.79 miles / hour

Output: Option D


Input: Consider Input: Question: Positive integer y is 50 percent of 50 percent of positive integer x, and y percent of x equals 100. what is the value of x ?

 Option A: 50

 Option B: 100

 Option C: 200

 Option D: 1000

 Option E: 2000


Output: Option C