Information of the boolean type only accepts Yes or No as an answer. It's very simple, yet very powerful, as there is no nuance possible whatsoever.
To know a client, it can be relevant to enquire whether the person is a member of a political party. In certain circumstances, this can result in additional risks.
There are only two available answers: yes, the client is a member of a political party, or no, the client is not. There is no grey area. That is why the boolean type is perfect for this field.