Synonyms

 [soften the sound]

Moot means debatable, open to discussion, or having no practical significance. Option C correctly identifies this core meaning of being arguable or questionable.

[deserving of honour]

Murk refers to darkness, gloom, or obscurity. Option C correctly identifies this meaning, while other options refer to substances or marks rather than atmospheric darkness.

[immensity]

[darkness]

[usually against]

Misappropriate means to take something dishonestly, especially funds or property, for unauthorized use. Option C correctly captures this meaning of dishonest taking, unlike simple misplacement or rudeness.

Eccentric means unconventional, peculiar, or departing from convention. Someone eccentric behaves in unusual or non-standard ways compared to societal norms.

Eclectic means deriving ideas, style, or taste from a broad and diverse range of sources. It refers to selecting from various different styles or approaches rather than a single school of thought.

Ecological means relating to the relationships between living organisms and their environment, or to the environment itself. It directly connects to environmental concerns and ecosystems.

Ecstatic means feeling or expressing overwhelming happiness or joyful excitement. Rapturous is a close synonym, both describing intense joy or bliss.

Efficacious means successful in producing a desired or intended result; effective. 'Working' captures the essence of something that produces the intended effect or gets the job done.

Effect means a result or consequence of an action. Outcome is the direct synonym - both refer to the end result of some cause or action.