Vacuous is lacking in ideas, intelligence and so on. Hence, bright is an antonym.

Correct Option: C

Vacuous is lacking in ideas, intelligence and so on. Hence, bright is an antonym.

Appease and placate are synonyms of propitiate.

Correct Option: A

Appease and placate are synonyms of propitiate.

Obdurate means obstinate or stubborn, hence compliant is the antonym.

Correct Option: C

Obdurate means obstinate or stubborn, hence compliant is the antonym.

As we know that ,
Opposite of enthusiasm would be nervousness,
Composure means calmness,
Dignity is calm and serious manner,
Brashness is opposite to composure.

Correct Option: D

As we know that ,
Elan means vigor or energy and enthusiasm, opposite of enthusiasm would be nervousness, composure means calmness, dignity is calm and serious manner while brashness is opposite to composure.
Hence , Nervousness is opposite of ELAN .

As we know that ,
Disinclination is opposite of Penchant word .

Correct Option: A

As we know that ,
Penchant is a natural inclination towards something, lone means only, alone, single.
Therefore , Disinclination is opposite of Penchant word .