How is an insurer best described?

An insurer is best described as any person, corporation, or society that writes insurance contracts because it encompasses the broad spectrum of entities involved in the insurance industry. This definition recognizes that insurers can take various forms, not limited to just corporations. This includes mutual insurance companies, stock insurers, and even some types of societies and individuals who are legally authorized to provide insurance products.

By allowing for this wider interpretation, option B acknowledges that different structures exist in the insurance market, each with unique characteristics. The insurance industry is diverse, and both corporate entities and non-corporate entities, such as mutual organizations or even self-insured groups, can qualify as insurers.

Other choices are too narrow. For example, stating that an insurer includes only corporations or only mutual insurance companies excludes a significant portion of the industry and does not reflect the modern understanding of how insurance is provided in various forms. Hence, option B is the most accurate and comprehensive description of an insurer.