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 510 m long is running at a speed of 45 km / hr. in what time will it pass a bridge 140 m long ?
Options: a. 40, b. 52, c. 26, d. 21, e. 14
[A]: b


[Q]: Problem: a fraudulent dairy guy declares to market his dairy at price range but he combined it with water and therefore benefits 25 %. the percentage of water in the combination is :
Options: a. 20 %, b. 30 %, c. 50 %, d. 35 %, e. 60 %
[A]: a


[Q]: Problem: 33 persons can repair a road in 12 days, working 5 hours a day. in how many days will 30 persons, working 6 hours a day, complete the work ?
Options: a. 10, b. 11, c. 13, d. 18, e. 19
[A]:
b