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: 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
[EX A]: Option A

[EX Q]: Question: A and B invests Rs.3000 and Rs.4000 respectively in a business. If A doubles his capital after 6 months. In what ratio should A and B divide that year's profit?

 Option A: 9:6

 Option B: 9:8

 Option C: 9:1

 Option D: 9:9

 Option E: 9:5
[EX A]: Option B

[EX Q]: Question: A train sets off at 2 p.m. at the speed of 68 kmph. Another train starts at 3:30 p.m. in the same direction at the rate of 85 kmph. At what time the trains will meet?

 Option A: 10:37 p.m

 Option B: 10:20 p.m

 Option C: 9:30 p.m

 Option D: 9:38 p.m

 Option E: 10:10 p.m
[EX A]:
Option C