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: A committee of 5 people is to be selected from 7 people. How many different committees are possible?

 Option A: 21

 Option B: 40

 Option C: 56

 Option D: D.168

 Option E: 336
[A]: Option A


[Q]: Question: Ajay marked the price of his goods 30% more than his C.P. He then sells 1/4th of his stock at a discount of 15%, and half of the stock at the marked price, and the rest at a discount of 30%. Find his gain percentage.

 Option A: 16.5%

 Option B: 15.375%

 Option C: 14.20%

 Option D: 13.37%

 Option E: None of these
[A]: Option B


[Q]: Question: Among 400 students, 56% study sociology, 44% study mathematics and 40% study biology. If 42% of students study both mathematics and sociology, what is the largest possible number of students who study biology but do not study either mathematics or sociology?

 Option A: 30

 Option B: 90

 Option C: 120

 Option D: 168

 Option E: 188
[A]:
Option D