Answer:
the evaluation of each other's efforts
Step-by-step explanation:
One key factor that can reduce social loafing appears to be "the evaluation of each other's efforts".
When people are in a group, they tend to put less effort in what that group is doing. This is known to be "social loafing". In this kind of situation, individuals in a group tend not to contribute maximally the way they should have done if they worked individually.
So, evaluating each other's efforts help to deal with social loafing. It will help them understand what their contributions are bringing to the group - progress or retrogression.