Questions

The meanings of the given words are as follows:
Histrionic: excessively theatrical or dramatic in character or style
Melodramatic: characteristic of melodrama, especially in being exaggerated or overemotional
Theatrical: exaggerated and excessively dramatic
Conscientious: wishing to do one's work or duty well and thoroughly
Diligent: having or showing care and conscientiousness in one's work or duties
Tenacious: tending to keep a firm hold of something; clinging or adhering closely
Retentive: (of a person's memory) effective in retaining facts and impressions
Thrive: (of a child, animal, or plant) grow or develop well or vigorously
Tussle: a vigorous struggle or scuffle, typically in order to obtain or achieve something
Pertinent: relevant or applicable to a
particular matter; apposite Appropriate: suitable or proper in the circumstances
Therefore, it can be observed that option  i.e. ‘melodramatic, theatrical’ forms a synonym- synonym pair of ‘histrionic’.

The meanings of the given words are as follows:
Tremulous: shaking or quivering slightly 

Stringent: (of regulations, requirements, or conditions) strict, precise, and exacting

Garrulous: excessively talkative, especially on trivial matters
Quivery: shaking or trembling slightly
Steady: firmly fixed, supported, or balanced; not shaking or moving
Conjunctive: relating to or forming a connection or combination of things
Desist: stop doing something; cease or abstain

Abstain: restrain oneself from doing or enjoying something
Defer: put off (an action or event) to a later time; postpone
Terse: sparing in the use of words; abrupt
Abrupt: sudden and unexpected
Therefore, it can be observed that option B i.e. ‘quivery, steady’ forms a synonym-antonym pair of ‘tremulous’.