The government provides insurance for individuals' bank deposits, but requires the banks to pay the premiums for this insurance. Since it is depositors who primarily benefit from the security this insurance provides, the government should take steps to ensure that depositors who want this security bear the cost of it and thus should make depositors pay the premiums for insuring their own accounts. Which one of the following principles, if established, would do most to justify drawing the conclusion of the argument on the basis of the reasons offered in its support? ['Any rational system of insurance must base the size of premiums on the degree of risk involved.', 'The people who stand to benefit from an economic service should always be made to bear the costs of that service.', 'The choice of not accepting an offered service should always be available, even if there is no charge for the service.', 'Government-backed security for investors, such as bank depositors, should be provided only when it does not reduce incentives for investors to make responsible investments.']