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.
--------
Question: Problem: the probability of two events a and b are 0.25 and 0.40 respectively. the probability that both a and b occur is 0.15. the probability that neither a nor b occur is _________
Options: a. 0.45, b. 0.4, c. 0.5, d. 0.05, e. 0.6

Answer: c

Question: Problem: if the range q of the 6 numbers 4, 314, 710 and x is 12, what is the difference between the greatest possible value of x and least possible value of x ?
Options: a. 0, b. 2, c. 12, d. 13, e. 15

Answer: d

Question: Problem: a fill pipe can fill 1 / 4 of cistern in 16 minutes. in how many minutes, it can fill 3 / 4 of the cistern ?
Options: a. 24 min, b. 30 min, c. 48 min, d. 26 min, e. 16 min

Answer:
c