If a and b are prime numbers, which of the following CANNOT be the value of ab? Choose the most appropriate option:
A) 9
B) 14
C) 21
D) 23
E) 25
23 is a prime number itself and so cannot be multiple of two prime numbers..   ANSWER:23
<result>D</result>
If a and b are prime numbers, which of the following CANNOT be the value of ab?