Which one of the descriptions is correct regarding the following Entity$-$Relationship diagram?

The union of MANUFATCTURE$\_$PART and PURCHASED PART totally covers PART.

MANUFATCTURE$\_$PART and PURCHASED PART should have their own key attributes, respectively.

An instance of PART cannot be a member of MANUFATCTURE$\_$PART and also a member of PURCHASED PART at the same time.

The diagram illustrates a mandatory$-$one$-$to$-$mandatory$-$many relationship.

MANUFATCTURE$\_$PART and PURCHASED PART do not inherit the attributes of PART.