Subgovernments are composed of key interest group leaders interested in policy X, the government agency in charge of administering policy X, and the handling policy X.

- Subcommittees.

Explanation:

The sub-governments are described as the governmental form that is secondary or subordinate to the central government. It comprises of the key interest group leaders who are attracted to policy X. The members of this government function as the agency of central government that is responsible for executing or administering the charge of policy X and handles the 'subcommittees' of policy X to ensure its execution and enforcement of policy that is prepared by the interest group. Thus, 'subcommittee' is the correct answer.

answer; membership group;