A. C will not be liable for abetment by conspiracy because C can only be held liable if he had concerted with A and B.
B. C would be liable for attempting to commit murder but not for committing murder because the poison was administered by A.
C. C is not liable for murder because he never conspired with A.
D. Though A and C have not conspire together yet C has been engaged in the conspiracy in pursuance of which Z has been murdered. C has, therefore, abetted the offence of murder and would be liable to the punishment of murder.
✅ The correct answer is option D.