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 train running at the speed of 60 km/hr crosses a pole in 21 seconds. What is the length of the train?

 Option A: 350 m

 Option B: 278 m

 Option C: 876 m

 Option D: 150 m

 Option E: 267 m
[EX A]: Option A

[EX Q]: Question: The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 kms in 4 hours, then the speed of the first train is:

 Option A: 70 km/hr

 Option B: 75 km/hr

 Option C: 84 km/hr

 Option D: 87.5 km/hr

 Option E: 88.5 km/hr
[EX A]: Option D

[EX Q]: Question: If 148/x is an integer and 108/x is an integer, which of the following must be true?
I. 9/x is an integer
II. 12/x is an integer
III. 36/x is an integer

 Option A: I only

 Option B: III only

 Option C: I and II only

 Option D: II and III only

 Option E: I, II and III
[EX A]:
Option C