John Jones Is in the Roofing Business and Enters into a Contact

John Jones is in the roofing business and enters into a contact with George Hopkins to put a new roof on George's house.John,who is extremely busy,decides to contract out the work to Albert.When Albert arrives,George refuses to let him do the work.In this case,under the contract

A) George can refuse to let Albert do the work.
B) Albert is merely John's agent.
C) either John or Albert can do the work.
D) George must permit Albert to do the work.
E) Albert is merely John's employee.