Fill in the blank with suitable words from the options. There is a general…

Concept: In a sentence-completion item joined by 'and', both blanks must carry the same direction and tone of meaning as the surrounding context: the conjunction signals continuation, not contrast, so a widely-shared view about one clause must pair with a word of the same emotional direction for the other blank, and the first blank must be a noun that naturally collocates with 'a general ___ that...'.

Application: The sentence already tells us the ethics are 'declining' - a negative trend. The first blank names the widely shared view about this ('general complaint' is the natural collocation for a broadly-held negative opinion), and the second blank must continue that same negative trend: 'deteriorating' parallels 'declining' exactly, so 'complaint - deteriorating' keeps both halves of the sentence consistent in meaning and tone.

Cross-check: Each of the other pairs breaks this required consistency:

• 'feeling - normalizing': 'normalizing' means settling into a stable, typical state, the opposite direction from 'declining', so it clashes with the sentence's negative framing.

• 'idea - futile': 'futile' describes an action as pointless, not a trend in moral standards, so it does not parallel 'declining' in sense.

• 'optimism - improving': 'optimism' is a hopeful, positive stance, which contradicts the sentence's premise that ethics are declining.

Only 'complaint - deteriorating' keeps the same negative direction and register across both blanks, matching the parallel structure set up by 'and'.