Leah and Mason Are Parties to a Contract for the Sale

Multiple Choice

Leah and Mason are parties to a contract for the sale of Mason's day care facility to Leah. Before the deal closes, they agree to substitute Nell for Leah as a party to the deal. This does not require

A) the existence of a previous, valid obligation.
B) agreement by all the parties to a new contract.
C) performance of the original contract by all of the parties.
D) a new, valid contract.