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.

Input: Consider Input: Question: Two trains are moving at 60 kmph and 70 kmph in opposite directions. Their lengths are 150 m and 100 m respectively. The time they will take to pass each other completely is?

Option A: 5 sec

Option B: 6 sec

Option C: 7 sec

Option D: 8 sec

Option E: 9 sec

Output: Option C

Input: Consider Input: Question: Which of the following CANNOT be weighed using a balance scale and these unit weights: 1, 4, 7, and 10

Option A: 13

Option B: 15

Option C: 17

Option D: 19

Option E: 21

Output: Option A

Input: Consider Input: Question: The mean of 15 observations was 25. It was found later that an observation 40 was wrongly taken as 25. The corrected new mean is

Option A: 20

Option B: 30

Option C: 15

Option D: 18

Option E: 26
Output: Option E