Which provision prevents an insurer from changing the terms of the contract with the policyowner by referring to documents not found within the policy itself?

Correct answer: (C)
The correct answer is "Entire contract provision". The entire contract provision, found at the beginning of the policy, states that the policy document, the application (which is attached to the policy), and any attached riders constitute the entire contract. Nothing may be "incorporated by reference," meaning that the policy cannot refer to any outside documents as being part of the contract.