$73-$ What do these examples prove? A contract exists between the plaintiff and a third party; $*$ Defendant knew of the contract; $*$ Defendant improperly induced the third party to breach the contract or made the performance of the contract impossible, and $*$ Plaintiff was injured.

a$-$prove unintentional interference with contractual relations

b$-$prove receiprocal interference with contractual relations

c$-$prove intentional interference with contractual relations

d$-$prove unreciprocal interference with contractual relations