which is always a cost when buying insurance?\npremium\ndeductible\nco - payment\npayout

Brief Explanations:

A premium is the amount an insured party pays regularly (e.g., monthly, annually) to an insurance company to keep the insurance policy in force. A deductible is an amount the insured pays out - of - pocket before insurance kicks in, but not always applicable. A co - payment is a fixed amount the insured pays for a covered service, also not always present. A payout is money the insurance company gives to the insured, not a cost to the insured.

Answer:

premium