Whatever opinion he gives is sane.

Answer: Option D

Arrogant : having or revealing an exaggerated sense of one's own importance or abilities.
Wild : (of an animal or plant) living or growing in the natural environment; not domesticated or cultivated.
Obscure : not discovered or known about; uncertain.
Rational : based on or in accordance with reason or logic.
Sane : (of a person) of sound mind; not mad or mentally ill.

Synonym of Sane is Rational