Which type of insurer does NOT provide insurance to the general public?

A captive insurer is structured specifically to provide insurance coverage to its parent company or group rather than to the general public. Essentially, it is a type of insurance company that is wholly owned by one or more non-insurance companies, created primarily to manage risk and provide customized insurance solutions for its owners. This model is beneficial for organizations looking to hedge against their specific risks without exposing themselves to the wide array of uncertainties present in the commercial insurance market.

In contrast, composite insurers, mutual insurers, and proprietary insurers all typically offer insurance products to the general public, serving a diverse array of clients and risks. Composite insurers can provide both life and general insurance products, mutual insurers are owned by policyholders and often aim to serve a broad demographic, while proprietary insurers are for-profit entities offering a variety of insurance services. Hence, the distinctive nature of a captive insurer in focusing solely on the insurance needs of its parent company highlights why this answer is the correct choice.