Which of the following situations can be seen as an application of leader$-$member exchange $($LMX$)$ theory?

Arnold, the factory manager of a manufacturer, continually attempts to maintain a good relationship with the factory workers.

A manager continually attempts to accomplish operational efficiency by rewarding only the better performers.

Sara, operations manager of a firm, successfully persuades employees to do well by offering rewards in exchange of good performance.

Ronald, the manager of a pharmaceutical company, performs a part of the operational tasks all by himself