It was presumptuous of him to make a remark in the assembly.

A. ridiculous

B. unthoughtful

C. self-confident

D. ambiguous

✅ The correct answer is option C.
Ridiculous : deserving or inviting derision or mockery; absurd.

Unthoughtful : showing little or no consideration for the needs of other people; thoughtless.

Overconfident : excessively confident.

Ambiguous : open to more than one interpretation; not having one obvious meaning.

Presumptuous : (of a person or their behaviour) failing to observe the limits of what is permitted or appropriate.

Synonym of Presumptuous is Overconfident

6431. It was presumptuous of him to make a remark in the assembly.