Use reasoning to answer the following question.
The inverse ratio of 9: 2: 1 is?\nOptions:\n(A) 1:9:18\n(B) 2:9:18\n(C) 2:7:18\n(D) 2:13:18\n(E) 2:9:15

(B)
1/9: 1/2: 1/1 = 2:9:18.

So, the answer is (B)