Come up with a question and reasoning that would justify this answer: (E)

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
The question is: Which one of the following is not a prime number?
Options:
(A) 51
(B) 61
(C) 71
(D) 82
(E) 91
Step-by-step reasoning process: 91 is divisible by 7. So, it is not a prime number.
