If each participant of a chess tournament plays exactly one game with each of the remaining participants, then 120 games will be played during the tournament. Find the number of participants.  Choose one: A) 15 B) 16 C) 17 D) 18 E) 19

Rationale: "let p be the number of participants . pc 2 = 120 ( p ) ( p - 1 ) = 240 = 16 * 15 p = 16 the answer is b ."
Answer: B