On whose behalf do most lobbyists work?

Public action committees (PACs), Bussinesses, Interest Groups, and unions.

Explanation:

Lobbyists are professional representatives who work on behalf of individuals and groups of individuals to influence political and legislative decisions in a government.They work for public action committees(PACs), Bussinesses, Interest Groups, and unions by persuading and pressurizing legislators and lawmakers to introduce and support bills in favor of such organizations.They play a vital role in policy and decision making progress and their participation helps in making amendments, new regulations, or even introducing new bill in the legislative.