Gregory is asked to perform a series of difficult and embarrassing tasks as initiation rites to a secret fraternity in his university. As a result of enduring these tasks, he is extremely loyal toward the fraternity. This strong group loyalty that Gregory feels is best explained by the concept of

effort justification.

Explanation:

Effort Justification is a phenomenon or an idea in which people believe that achievement of a goal is worthwhile only if they had worked hard to achieve that goal. Effort Justification is stemmed from the psychological theory of cognitive dissonance.

In simple terms, loving to do those tasks which make them suffer only to achieve the goal.

In the given case of group initiation rites, Gregory is asked to perform a series of difficult and embarrassing tasks. After the successful completion of these embarrassing tasks, Gregory was considered extremely loyal towards the group. This is an example of effort justification.  

So, the correct answer is effort justification.

stewards ice box was the purchase of alaska from russia and it was called that because people thought it was not a good idea to purchase alaska