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 T that this product will be a multiple of 45?  Choose the correct choice from the following options:
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 t = 1 / 24 . answer c ."
Answer: C