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 125m long takes 6 sec to cross a man walking at 5kmph in a direction opposite to that of the train. Find the speed of the train?

 Option A: 65kmph

 Option B: 70kmph

 Option C: 75kmph

 Option D: 80kmph

 Option E: 85kmph
[EX A]: Option B

[EX Q]: Question: If each of 4 digit code is formed of integers from 1 to 50, inclusively, and each of the digits are different, how many possible codes are there?

 Option A: 5527200

 Option B: 5586300

 Option C: 5598600

 Option D: 5547800

 Option E: 2569800
[EX A]: Option A

[EX Q]: Question: If m and n are positive integers, and m=2n and k=m, then -

 Option A: m/2 is a factor of k.

 Option B: 2m is a factor of k.

 Option C: 3m is a factor of k/2.

 Option D: k is a factor of m.

 Option E: k is a factor of m/2.
[EX A]:
Option A