There are 12 slate rocks, 17 pumice rocks, and 8 granite rocks randomly distributed in a certain field. If 2 rocks are chosen at random and without replacement, what is the probability that both rocks will be slate rocks?  Pick one:
A) 5 / 36  B) 7 / 64  C) 9 / 83  D) 11 / 111  E) 13 / 135

Rationale: "12 / 37 * 11 / 36 = 11 / 111 the answer is d ."
Answer: D