Which of these sets consists entirely of prime numbers?

Question

(A)3, 7, 5, 2, 8
(B)5, 11, 13, 41, 61
(C)19, 17, 20, 11, 13
(D)23, 31, 37, 27, 41

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Answer 1 · 2018-04-10T20:52:08

Let's use elimination:

(A) has 8=2x2x2
(C) has 20=2x2x5
(D) has 27=3x3x3

Answer:
(B) and they're all primes (I checked extra)

Note:
(A) and (C) were easy: no even number (except 2) can be a prime.