Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[Q]: Problem: a train of length 250 m crosses a bridge of length 150 m in 20 seconds. what is the speed of train ?
Options: a. 33, b. 27, c. 25, d. 22, e. 72
[A]: e

[Q]: Problem: if a person walks at 25 km / hr instead of 10 km / hr, he would have walked 20 km more. the actual distance traveled by him is :
Options: a. 50 km, b. 56 km, c. 13.3 km, d. 70 km, e. 80 km
[A]: c

[Q]: Problem: a milk man has 40 liters of milk. if he mixes 5 liters of water, which is freely available, in 20 liters of pure milk. if the cost of pure milk is rs. 18 per liter, then the profit of the milkman, when he sells all the mixture at cost price is :
Options: a. 20 %, b. 25 %, c. 45 %, d. 18 %, e. none of these
[A]:
c