The correct answer is C. conciliatory.
A conciliatory action is one that is intended to bring about peace or agreement between two or more parties. In the context of the question, the labour officer intervened to try to bring the plantation workers and their employers to an agreement. This is an example of a conciliatory action.
The other options are not correct because they do not describe the labour officer’s actions accurately. A circuitous action is one that is indirect or roundabout. A retaliatory action is one that is taken in revenge for something that has been done. A perfunctory action is one that is done without care or attention to detail.
In conclusion, the correct answer is C. conciliatory.