The correct answer is D.
The commitees in the US Congress are legislative sub-organizations, and each develops specialized knowledge on its subject (Agriculture, Armed Services, or Financial Services, for example).
The comitees supervise on-going governmental operations, identify matters that should be analized through legislative review, they compare and evaluate legislative alternatives; identify policy problems and propose possible solutions and they recommend courses of action to be discussed in the Congress chambers.
Comitees are fundamental and completely inherent to the legislative process undertaken in Congress, as it is not possible that Congress members are specialists on every subject discussed in the chambers and therefore they have to rely on the valuable information elaborated by the comitees in order to reach appropiate decisions.