Question 34
In a certain school, there is a committee consisting of 4 members. There are 4 sub-committees for this committee, and each committee member will be asked to chair a different sub-committee. Suppose each committee member has 2 sub-committees he prefers to chair. It is known that there are exactly 2 ways to assign sub-committees to members in such a way to satisfy the preferences of all the members. How many possible combinations of the preferences of all four members are there in this situation?