You Have a PV Diagram for a Device Going Through

Multiple Choice

You have a PV diagram for a device going through a cyclic process forming a closed loop on the diagram.How can you tell from the diagram whether the device is acting as a heat engine and not as a refrigerator?

A) The loop is longer than it is high which means it is acting as a refrigerator.
B) The loop is higher than it is long which means it is acting as a refrigerator.
C) The loop proceeds clockwise which means it is acting as a heat engine.
D) The loop proceeds counterclockwise which means it is acting as a heat engine.