Final answer:
Agents are the option retained at the expense of an insurance buyer to give advice on insurance needed by the buyer.
Step-by-step explanation:
The option retained at the expense of an insurance buyer to give advice on insurance needed by the buyer is d) Agents.
Agents are representatives of insurance companies who work directly with buyers to understand their insurance needs and provide advice on suitable policies. They help buyers navigate through the insurance process and make informed decisions about their coverage options.