If a randomly selected positive single digit multiple of 3 is multiplied by a randomly selected prime number less than 20, what is the probability E that this product will be a multiple of 45?
Select.
A) 1 / 32 B) 1 / 28 C) 1 / 24 D) 1 / 16 E) 1 / 14

Rationale: "there are 3 single digit multiple of 3 , that is , 3 , 6,9 . there are 8 prime nos less than 20 - 2,3 , 5,7 , 11,13 , 17,19 total outcome - 8 * 3 = 24 favourable outcome = 1 ( 9 * 5 ) hence required probability e = 1 / 24 . answer c ."
Answer: C