You need to let the landlord do this for you, or advise you how he wants it done. You're going to have to change the cord on your dryer, most likely. I seriously doubt the landlord will change the circuit to a 3 wire circuit. H-H-N-G. However, You may have conduit instead of cable in an apartment building. This would make it very easy for him to supply you with 3 wires, and the correct receptacle. The 4 wire cord is correct. The old 3 wire was never correct.