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.

[EX Q]: Question: Rs.8000 become Rs.11256 in a certain interval of time at the rate of 5% per annum of C.I. Find the time?

Option A: 6 YEARS

Option B: 7

Option C: 5

Option D: 3

Option E: 4
[EX A]: Option B

[EX Q]: Question: The greatest common factor of 16 and the positive integer n is 4, and the greatest common factor of n and 45 is 3. Which of the following could be the greatest common factor of n and 210?

Option A: 3

Option B: 14

Option C: 30

Option D: 42

Option E: 70
[EX A]: Option D

[EX Q]: Question: A person can walk at a constant rate of 8mph and can bike at a rate of 16mph. If he wants to travel 72 miles in 8 hours using bike and walking at their constant rates, how much distance would he require to walk?

Option A: 20

Option B: 30

Option C: 48

Option D: 56

Option E: 72
[EX A]:
Option D