a light flashes every 20 seconds, how many times will it flash in ? of an hour? Select the correct option: A) 550 B) 600 C) 650 D) 180 E) 750

Rationale: "1 flash = 20 sec for 1 min = 3 flashes so for 1 hour = 3 * 60 = 180 flashes . answer : d"
Answer: D