In the US, this practice is prohibited by the Robinson-Patman Act when it causes “primary line” competitive injury across state borders. (10[1])Marcel Boiteux (“bwah-TUH”) built upon Frank Ramsey’s finding that this practice may maximize social welfare. The two-part tariff is an example of this practice in which a product has both lump-sum and per-unit components. (-5[1])The third-degree version of this (10[1])practice relies on an exogenous signal to segment a market. When this practice is performed perfectly, deadweight loss (-5[1])and consumer surplus are eliminated. This practice usually (10[1])disadvantages consumers (10[1])with lower elasticities of demand. For 10 points, name this practice exemplified by senior discounts, in which a firm charges different amounts to different customers. ■END■ (10[3]0[1])