Cancel the order in the system.
This really isn't hard. It's a process of elimination. Of the four choices listed, "Cancel the order in the system" was the only one that Rachel was given instructions to do.
The first answer can be eliminated because Rachel was instructed to pick up the FedEx package from Rhonda and set it on Marcus' desk. Her instructions were not to delegate the task to Rhonda.
The second answer can be eliminated because the instructions were for Roy to call store 789.
The fourth answer can be eliminated because it is Roy that is supposed to stop by store 789 and pick up the power washer kit, not Rachel.
Maybe they are testing to see how well one can listen to and understand instructions. Or perhaps it is a matter of how well one follows instructions. Regardless, there really is only the one correct answer.