It's not A. The party with the Most members is the power in power.
Sometimes it is B, especially when there is a coalition government. The party with the most members will off some legislation to keep the second (minority power) in line. By and large you are expected to say no to this answer.
C is probably the answer they are looking for. It is a for sure answer, other wise it would not exist.
D it might, but the party in power must hold some of this or they would not be elected.