Which one of the following is a correct statement regarding cost-of-living increases to Social Security benefits? A) Increases in Social Security benefits resulting from cost-of-living increases are not effective until the start of the next year. B) Indexed Social Security benefits actually increase slightly faster than the cost-of-living index. C) Social Security benefits are indexed to the cost of living on a semiannual basis. D) Social Security benefit increases must be approved by Congress quarterly