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.

[Q]: Question: man buys an article for 10% less than its value and sells it for 10% more than its value. His gain or loss percent is?

 Option A: 12

 Option B: 76

 Option C: 26

 Option D: 20

 Option E: 12
[A]: Option D


[Q]: Question: A can run 192 metre in 28 seconds and B in 32 seconds. By what distance A beat B?

 Option A: 38 metre

 Option B: 28 metre

 Option C: 24 metre

 Option D: 15 metre

 Option E: 28 metre
[A]: Option C


[Q]: Question: The average age of 36 students in a group is 14 years. When teacher's age is included to it, the average increases by one. What is the teacher's age in years ?

 Option A: 81 years

 Option B: 21 years

 Option C: 51 years

 Option D: 31 years

 Option E: 61 years
[A]:
Option C