A bag contains 4 green and 8 white balls. If two balls are drawn simultaneously, the probability that both are of the same colour is	Choose the correct choice from the following choices:	A) 8 / 15	B) 2 / 5	C) 3 / 5	D) 11 / 15	E) 17 / 33

Rationale: "drawing two balls of same color from four green balls can be done in 4 c ₂ ways . similarly from eight white balls two can be drawn in ⁸ c ₂ ways . p = 4 c ₂ / ¹ ⁵ c ₂ + ⁸ c ₂ / ¹ ⁵ c ₂ = 17 / 33 answer : e"
Answer: E