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: A rectangular plot measuring 90 metres by 50 metres is to be enclosed by wire fencing. If the poles of the fence are kept 10 metres apart, how many poles will be needed ?

 Option A: 28

 Option B: 56

 Option C: 57

 Option D: 58

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

[EX Q]: Question: A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^5, then what was the number in the population 50 minutes later?

 Option A: 2(10^5

 Option B: 5(10^5

 Option C: (2^5

 Option D: (10^5

 Option E: (10^5
[EX A]: Option C

[EX Q]: Question: The average (arithmetic mean) of the 5 positive integers k, m, r, s, and t is 12, and k < m < r < s < t. If t is 20, what is the greatest possible value of the median of the 5 integers?

 Option A: 16

 Option B: 18

 Option C: 19

 Option D: 20

 Option E: 22
[EX A]:
Option D