Answer:
One to One Relationship
Explanation:
Given that in a computer systems analysis about an entity-relationship model, a one-to-one relationship is a form of cardinality that involves the relationship that exists between two different entities Y and Z, such that one element Y can only be associated with one element Z, or in the other way round.
Hence, the cardinality of the friend_of relationship set between two student entities in the student entity set should be: "One to One Relationship"
