Description of my belief or behavior

Belief is to have the acceptance that somthing is true or real it's like having faith in somthing with or without proof it exists

Belief: an acceptance that something exists or is true, especially one without proof.

trust, faith, or confidence in (someone or something).

behaviour: the way in which one acts or conducts oneself, especially towards others.

the way in which an animal or person behaves in response to a particular situation or stimulus.

the way in which a machine or natural phenomenon works or functions

Not b or c so that leaves you with a or d. a is the better choice.