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: 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

[EX Q]: Question: A car going at 40 miles per hour set out on an 90-mile trip at 9:00 A.M. Exactly 10 minutes later, a second car left from the same place and followed the same route. How fast, in miles per hour, was the second car going if it caught up with the first car at 10:30 A.M.?

 Option A:  45

 Option B:  50

 Option C:  53

 Option D:  55

 Option E:  90
[EX A]: Option E

[EX Q]: Question: A customer using a certain telephone calling plan pays a fee of $25 per month, and then receives a discount of 40% on the regular charge for all calls made to country X. If calls to country X are regularly charged at $1.60 per minute for the first 3 minutes, and $0.80 per minute for each minute thereafter, what is the maximum the customer could have saved over regular prices if he was charged for 1 hour of calls made to country X in a certain month?

 Option A: $8.75

 Option B: $12

 Option C: $13.40

 Option D: $17.40

 Option E: $24.40
[EX A]:
Option C