Thread: Reflexive relations proof

Im stuck on this hw problem. Can someone pleae help me.

Recall that a relation on a set is reflexive if and only if the diagonal is a subset of the relation. In both 1 & 2, can the diagonal remain after the set operation?
A relation that has an empty intersection with the diagonal is irreflexive.

Look carefully at the definition of relational composition.
Because both R & S contain the diagonal, must SoR also?