
Here's a detailed solution to the given problem in a CKEditor-compatible HTML format: ```html
To find the work done by the system in the cyclic process ABCDA, we need to look closely at the pressure-volume (P-V) diagram provided.
In a PV diagram, the work done by a system during a process is represented by the area enclosed by the process path. For a cyclic process, the work done is given by the net area enclosed by the cycle in the PV diagram.
As a result, the net work done by the system in this specific cyclic process (ABCDA) is zero.
Therefore, the correct answer is: Zero.
``` This solution considers the symmetries and properties of the cyclic process to derive the conclusion accurately, in line with principles of thermodynamics.