Correct Answer: mandatory

Solution : The correct choice is the third option.

Explanation : "Voluntary" implies an action or decision made willingly, without coercion or external pressure. To find an antonym, we should look for a term that denotes actions or situations that are obligatory or required. "Mandatory" fits this criterion, as it signifies something that must be done or is required by law or rule.

Therefore, the correct antonym is mandatory .

The meanings of the other options are as follows:

• Discretional : This term refers to something left to one's discretion or choice.
• Optional : This term indicates something that is available as a choice.
• Uncompelled : This word suggests a lack of coercion or force.