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.

Problem: the salary of a person was reduced by 14 %. by what percent should his reduced salary be raised so as to bring it at par with his original salary ?
Options: a. 10 %, b. 16.3 %, c. 13.7 %, d. 15.1 %, e. 12.3 %
b

Problem: if 50 apprentices can finish a job in 4 hours, and 30 journeymen can finish the same job in 8 hours, how much of the job should be completed by 10 apprentices and 15 journeymen in one hour ?
Options: a. 1 / 9, b. 29 / 180, c. 9 / 80, d. 1 / 5, e. 39 / 121
c

Problem: the product z of two prime numbers is between 16 and 40. if one of the prime numbers is greater than 2 but less than 6 and the other is greater than 12 but less than 30 then what is z ?
Options: a. 21, b. 22, c. 28, d. 35, e. 39
e