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 man can do a piece of work in 5 days, but with the help of his son he can do it in 3 days. In what time can the son do it alone ?

Option A: 13/2

Option B: 19/2

Option C: 21/2

Option D: 15/2

Option E: None
[EX A]: Option C

[EX Q]: Question: In a certain Gun shooting competition prizes were awarded as follows: the first place winner receives 11 points, the second place winner receives 7 points, the third place winner receives 5 points and the fourth place winner receives 2 points . No other points were awarded. John participated several times in the competition. The product of all the points he received was 84700. How many times did he participate in the competition.

Option A: 7

Option B: 5

Option C: 3

Option D: 2

Option E: cannot be determined
[EX A]: Option E

[EX Q]: Question: an article with cost price of 180 is sold at 15% profit. what is the selling price?

Option A: 198

Option B: 200

Option C: 204

Option D: 207

Option E: 210
[EX A]:
Option D