RC Willey, a multi$-$store furniture retailer, allows its marketers to employ a low$-$price tactic because$--$based on high$-$volume purchases, they pay $$40$ less per La$-$Z$-$Boy Rocker than does Robbie's Rockers, a small, independent specialty furniture and RC Willey's primary competitor for the same product. This is a case of $\_\_\_\_\_\_\_\_\_\_\_\_$ and it is$\_\_\_\_\_\_\_\_\_\_\_\_.$

RC Willey, a multi$-$store furniture retailer, allows its marketers to employ a low$-$price tactic because$--$based on high$-$volume purchases, they pay $$40$ less per La$-$Z$-$Boy Rocker than does Robbie's Rockers, a small, independent specialty furniture and RC Willey's primary competitor for the same product. This is a case of $\_\_\_\_\_\_\_\_\_\_\_\_$ and it is$\_\_\_\_\_\_\_\_\_\_\_\_.$

horizontal price discrimination; legal

vertical price discrimination; illegal

vertical price discrimination; legal

horizontal price discrimination; illegal

predatory pricing; illegal