The sum of the prime factors of 42 is
(A) 23
(B) 43
(C) 12
(D) 17
(E) 13
Since 42 is an even number, then 2 is a factor of 42 .

Since $42=2 \times 21$ and $21=3 \times 7$, then $42=2 \times 3 \times 7$.

Each of 2, 3 and 7 is a prime number and each is a factor of 42 .

Thus, the sum of the prime factors of 42 is $2+3+7=12$.

(We note that 1,6,14,21, and 42 are also factors of 42 , however they are not prime numbers.)

ANSWER: (C)