Zeta Contracts to Perform a Violin Solo for Pat

Zeta contracts to perform a violin solo for Pat.Zeta assigns the contract to Roy.Is this a valid delegation of duty?

A) There is no valid delegation of Zeta's duty to play because all delegations must be expressly stated in the assignment contract.
B) There is no valid delegation of Zeta's duty to play because the contract is one in which Zeta's personal skill as a musician is an essential part of the agreement.
C) There is a valid delegation of Zeta's duty as Zeta has entered into a novation with Roy.
D) There is a valid delegation of Zeta's duty because Zeta does not want to play for Pat.