Concept:A society is a group of people who come together for shared purposes, and joining such a group is based on personal choice.
Explanation:Membership of a society is never forced on anyone.
People decide freely to join because of common interests or goals.
It is not constitutional because it is not imposed by a law or legal provision.
It is not conventional merely because it follows a custom or tradition.
It is not mandatory, since no one is compelled to belong against their will.
Therefore, belonging to a society is a matter of free personal decision, which makes it voluntary.
Answer:A. voluntary