Grant and Debbie enter into a contract binding Grant personally to do some delicate cabinetwork. Grant assigns his rights and delegates performance of his duties to Clarence.

a. On being informed of this, Debbie agrees with Clarence, in consideration of Clarence's promise to do the work, that Debbie will accept Clarence's work, if properly done, instead of the performance promised by Grant. Later, without cause, Debbie refuses to allow Clarence to proceed with the work, though Clarence is ready to do so, and makes demand on Grant that Grant perform. Grant refuses. Can Clarence recover damages from Debbie? Can Debbie recover from Grant?

b. Instead, assume that Debbie refuses to permit Clarence to do the work, employs another carpenter, and brings an action against Grant, claiming as damages the difference between the contract price and the cost to employ the other carpenter. Explain whether Debbie will prevail.