In a room filled with 7 people, 4 people have exactly 1 sibling in the room and 3 people have exactly 2 siblings in the room. If two individuals are selected from the room at random, what is the probability that those two individuals are NOT siblings?	Choose the correct choice from the following answers:
A) 5 / 21 B) 3 / 7 C) 4 / 7 D) 5 / 7 E) 16 / 21

Rationale: "# of selections of 2 out of 7 - c 27 = 21 c 72 = 21 ; # of selections of 2 people which are not siblings - c 12 ∗ c 12 c 21 ∗ c 21 ( one from first pair of siblings * one from second pair of siblings ) + c 12 ∗ c 13 c 21 ∗ c 31 ( one from first pair of siblings * one from triple ) + c 1 ^ _ 2 * c ^ 1 _ 3 ( one from second pair of siblings * one from triple ) = 4 + 6 + 6 = 16 = 4 + 6 + 6 = 16 . p = 16 / 21 answer : e"
Answer: E