This painting is full of radiant colours.

Answer: Option B

Radiant : sending out light; shining or glowing brightly.
Delicate : very fine in texture or structure; of intricate workmanship or quality.
Dull : lacking brightness, vividness, or sheen.
Bright : giving out or reflecting much light; shining.
Rare : (of an event, situation, or condition) not occurring very often.

Antonym of Radiant is Dull