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: The least number of complete years in which a sum of money put out at 20% C.I. will be more than doubled is?

 Option A: 3

 Option B: 4

 Option C: 9

 Option D: 3

 Option E: 5
[A]: Option B


[Q]: Question: A reduction of 25% in the price of oil enables a house wife to obtain 5kgs more for Rs.800, what is the reduced price for kg?

 Option A: 72

 Option B: 27

 Option C: 40

 Option D: 28

 Option E: 20
[A]: Option C


[Q]: Question: A rope of which a calf is tied is increased from 5m to 9 m, how much additional grassy ground shall it graze?

 Option A: 1218

 Option B: 180

 Option C: 176

 Option D: 200

 Option E: 291
[A]:
Option C