Which is a way to control extraneous variables?

All but which of the following are consistent with the pluralist model of democracy?

A. The content of a bill can be changed at any stage of the process. B. At least some members of a committee are advocates of the programs they oversee. C. Representatives are elected by voters from particular districts and states. D. Party leadership rewards congressmen who vote a party line with better committee assignments. E. The president controls the use of filibusters.

To affect the political process, it is important to understand

a. the institutional structures. b. the informal norms of operation. c. successful past strategies. d. a candidate's biography.