20 beavers, working together in a constant pace, can build a dam in 6 hours. How many hours will it take 12 beavers that work at the same pace, to build the same dam?  Choose the correct choice from the following:  A) 10 .  B) 4 .  C) 5 .  D) 6  E) 8 .

Rationale: "total work = 20 * 6 = 120 beaver hours 12 beaver * x = 120 beaver hours x = 120 / 12 = 10 answer : a"
Answer: A