Question 155
A group of 16 people will be partitioned into 4 indistinguishable 4-person committees. Each committee will have one chairperson and one secretary. The number of different ways to make these assignments can be written as $3^r M$, where $r$ and $M$ are positive integers and $M$ is not divisible by 3. What is $r$?
(A) 5 (B) 6 (C) 7 (D) 8 (E) 9
(A) 5 (B) 6 (C) 7 (D) 8 (E) 9