18 beavers, working together in a constant pace, can build a dam in 12 hours. How many hours will it take 12 beavers that work at the same pace, to build the same dam?	Choose the correct choice:
A) 2 .
B) 4 .
C) 5 .
D) 6
E) 18 .

Rationale: "total work = 18 * 12 = 216 beaver hours 12 beaver * x = 216 beaver hours x = 216 / 12 = 18 answer : e"
Answer: E