His was a sulky disposition.

Answer: Option B

Sulky : morose, bad-tempered, and resentful; refusing to be cooperative or cheerful.
Mild : not severe, serious, or harsh.
Cheerful : noticeably happy and optimistic.
Loving : feeling or showing love or great care.
Kind : a group of people or things having similar characteristics.

Antonym of Sulky is Cheerful