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: 8 persons can build a wall 140m long in 42 days. In how many days can 30 persons complete a similar wall 100 m long?

 Option A: 12

 Option B: 10

 Option C: 8

 Option D: 6

 Option E: 5
[A]: Option C


[Q]: Question: A and B invests Rs.3000 and Rs.4000 respectively in a business. If A doubles his capital after 6 months. In what ratio should A and B divide that year's profit?

 Option A: 9:6

 Option B: 9:8

 Option C: 9:1

 Option D: 9:9

 Option E: 9:5
[A]: Option B


[Q]: Question: For which of the following functions is f(e+b)=f(e)+f(b) for all positive numbers e and b?

 Option A: a

 Option B: b

 Option C: c

 Option D: d

 Option E: e
[A]:
Option E