To commit someone to a mental institution for an indefinite period of time, an individual must be deemed either or

The answer in the space provided is mentally ill and a threat towards self or others. It is because this two things are one of the reasons in committing someone in a mental institution as they are in need of medical help that will help them mentally as they can't do it on their own.

Ithink the answer is b. shakeri hope im not wrong : )