What Is the Warranty of Assignability at Common Law

What is the warranty of assignability at common law?

A) That when a party "assigns" a contract to another party,the assignor is expressly guaranteeing a warranty of merchantability for fitness.
B) That when a party "assigns" a contract to another party,the assignor is impliedly guaranteeing that the rights being assigned are valid.
C) That when a party "assigns" a contract to another party,the assignor is impliedly providing a warranty of merchantability.
D) That when a party "assigns" a contract to another party,the person being assigned contractual rights expressly agrees to provide consideration.
E) That when a party "assigns" a contract to another party,the assignor is impliedly guaranteeing a warranty of fitness for a particular purpose.