Answer
In each cycle, the cycle should be traversed clockwise.
Work Step by Step
We can write an expression for the work done by a gas:
$W = \int_{V_i}^{V_f}~p~dV$
Note that if the volume does not change, then the work done by the gas is zero. Thus the work done by a gas along each vertical section is zero.
For the net work to be positive, we should move around the diagram so that the section at higher pressure moves from a lower volume to a higher volume.
In each cycle, the cycle should be traversed clockwise.
