The insuring agreement is one of the most essential components of an insurance policy. It describes what is insured, the coverage provided, and the extent of the insurer's promise to indemnify the insured. This section outlines the subject of insurance---property, liability exposure, person, or interest---and specifies what types of losses or perils are insured against. Thus, the accurate choice is D: Description of the property covered.

Option A is incorrect because premium is stated in the declarations page, not in the insuring agreement. Option B, lienholder information, also appears in the declarations or conditions, not the insuring agreement. Option C, the signature clause, appears at the end of the policy to signify the insurer's formal acceptance of contractual obligations.

The insuring agreement is the foundation of the policy because it establishes the insurer's undertaking and sets the boundaries of coverage, making option D correct.