Bill and Charlene Enter into a Contract for the Clearing,plowing,and

Bill and Charlene enter into a contract for the clearing,plowing,and preparing of Charlene's 100-acre tract for which she agrees to pay $1,000.Bill transfers his duty under this contract to Dewey.With respect to the duties under the original contract,this transfer

A) does not relieve Bill of the potential obligation to perform.
B) extinguishes Bill's obligation to perform.
C) is an invalid transfer of a non-transferable obligation.
D) requires a special form to constitute a valid transfer.