Concept:An agent whose authority has no limit is one who can perform every lawful act on behalf of the principal.Explanation:A del credere agent only guarantees payment for credit sales.A special agent is appointed for one specific transaction or purpose.A general agent has wide powers, but only within a particular trade or business.A universal agent, however, has unrestricted authority to do all acts that the principal can lawfully do.Therefore, the agent with unlimited authority is the universal agent.Answer:D. universal agent