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 combustion reaction forms carbon dioxide. A carbon dioxide molecule contains one carbon and two oxygen atoms. If, over a period of 10 minutes, a combustion reaction creates 10,000 molecules of carbon dioxide then approximately how many more atoms of oxygen than carbon are created on average per minute?

 Option A: 1,000

 Option B: 500

 Option C: 250

 Option D: 50

 Option E: 0
[EX A]: Option A

[EX Q]: Question: A sum of Rs.4800 is invested at a compound interest for three years, the rate of interest being 10% p.a., 20% p.a. and 25% p.a. for the 1st, 2nd and the 3rd years respectively. Find the interest received at the end of the three years?

 Option A: Rs.3129

 Option B: Rs.3120

 Option C: Rs.3108

 Option D: Rs.3106

 Option E: Rs.3127
[EX A]: Option B

[EX Q]: Question: Mary works in a restaurant a maximum of 70 hours. For the first 20 hours, she is paid $8 per hour. For each overtime hour, she is paid at a rate which is 25% higher than her regular rate. How much Mary can earn in a week?

 Option A: 600

 Option B: 620

 Option C: 660

 Option D: 320

 Option E: 400
[EX A]:
Option C