Suppose a database has an entity called Animals and another called Mammals.

What relationship would you expect there to be between them?

$1.$ There is a one$-$to$-$one relationship between them.

$2.$ There is a many$-$to$-$many relationship between them.

$3.$ Animals is the supertype, and Mammals is the subtype.

$4.$ Mammals is the supertype, and Animals is the subtype.