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 (-5[1])is an example of this practice in which a product has (10[1])both lump-sum and (10[1])per-unit components. (-5[3])The third-degree (-5[1])version of this (10[1])practice relies on (10[2])an exogenous signal to segment a market. (-5[1])When this practice is performed perfectly, deadweight (-5[1])loss (-5[1])and consumer surplus (-5[1])are (-5[1])eliminated. (-5[1])This practice (-5[2])usually (10[1])disadvantages consumers (10[1]0[1]-5[2])with lower elasticities of demand. (-5[1])For 10 points, name this practice exemplified by senior discounts, (10[1])in which a firm (10[1])charges different amounts to different customers. (10[2])■END■ (10[8]0[9])