The ____ is a certificate that adds to or changes the coverage of an insurance policy.

The correct choice emphasizes that a certificate known as an endorsement modifies or adds to the terms of an insurance policy. Endorsements are used by insurers to clarify, add, or remove specific coverage areas, terms, or conditions within an existing policy. They serve as officially attached documents that alter the original agreement between the insurer and the insured, thereby affecting how coverage applies in various situations.

In the context of insurance, endorsements are vital because they can tailor a policy to the unique needs of the insured, ensuring that specific circumstances or additional risks are adequately covered. This flexibility is important for both policyholders seeking comprehensive protection and insurers managing their risk exposure.

The other options refer to different concepts in insurance. An exclusion outlines what is not covered by the policy, a rider typically refers to an additional provision granting extra coverage or benefits (but is used in a slightly different context from an endorsement), and a condition specifies the requirements that must be met for a policy to remain in effect. Each of these plays a critical role in the overall structure of an insurance agreement but does not specifically refer to the modification or addition of coverage like an endorsement does.