A bag contains 7 red, 5 blue and 4 green balls. If 2 ballsare picked at random, what is the probability that both are red?
Choose the correct choice from the following:
A) 2 / 15 B) 2 / 21 C) 7 / 40 D) 3 / 29 E) 4 / 27

Rationale: "p ( both are red ) , = 7 c 216 c 2 = 7 c 216 c 2 = 21 / 120 = 7 / 40 c"
Answer: C