What Function Do Interest Groups and Think Tanks Serve in the Policymaking

What function do interest groups and think tanks serve in the policymaking process?

A) They lobby the president to pressure him into signing a bill into law at the adoption stage of the policymaking process.
B) They bring attention to issues and policies to solve those issues for Congress to consider as part of the recognition stage.
C) They provide Congress with research to demonstrate that those policies are effective in practice as part of the implementation stage.
D) They give members of Congress money to give priority to certain issues and policies as part of the formulation stage.