Preventing a Layer from showing if another layer is triggered first

Hi. I'm working on a project where layer A (Correct) is triggered if the learner clicks on the correct object. If they don't click on it before a motion path ends, a different layer B (INCORRECT) is triggered. Is there a way to set a variable or trigger that ensures the layer B doesn't show if layer A does? 

Right now, Layer B is triggered if the motion path completes before the learner clicks on the correct object. That continues to play in the background while Layer A appears. I need a way to cancel the motion path on the learner clicking the correct object, or set it so that Layer A appearing cancels Layer B from appearing regardless of the motion path completing. 

Appreciate any help. 

Traci