How Does an Iron Triangle Work in Creating Change in Public

How does an iron triangle work in creating change in public policy?

A) Members of Congress protect their constituencies and interest groups;constituencies reelect the congressional representatives and give money to interest groups;and interest groups support members of Congress and their constituencies.
B) Interest groups provide funds to members of Congress and their constituencies,who in turn pressure the president to push through policies the interest groups want,at which point constituencies will give their economic support to interest groups.
C) Members of Congress protect agencies and interest groups;agencies give special services to interest groups and congressional representatives' constituencies;and interest groups support members of Congress and agencies.
D) Agencies supply services to the public and,in return,the public supports agency activities,which puts pressure on Congress to pass laws in favor of the agencies.