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: Look at this series: 15, 15, 27, 27, 39, 39, 51, 51, 63, 63, ? ... What number should fill the blank?

 Option A: 51

 Option B: 39

 Option C: 75

 Option D: 15

 Option E: None
[EX A]: Option C

[EX Q]: Question: If a light flashes every 6 seconds, how many times will it flash in 1/4 of an hour?

 Option A: 51

 Option B: 151

 Option C: 251

 Option D: 351

 Option E: 451
[EX A]: Option B

[EX Q]: Question: 5% of a number is more than 20% of 650 by 190. Find the number?

 Option A: 288

 Option B: 278

 Option C: 800

 Option D: 267

 Option E: 6400
[EX A]:
Option E