If the US System of Single-Member Districts with Plurality Voting Were Replaced

If the U.S. system of single-member districts with plurality voting were replaced with a system of proportional representation, one possible consequence would be:

A) Greater centralization of power in the hands of the president.
B) Establishment of stronger interest groups.
C) The disappearance of political parties.
D) A movement toward a multiparty system.
E) The responsible party system.