Idiomatic noun choice – moral hesitation vs. ethical terms: choose the best noun for "felt no ____". Sentence: "He felt no ______ as he plunged the knife into her back." Select the noun that idiomatically follows "no" to mean "no moral hesitation or misgiving".

Given data

• The idiom is "no qualms about (doing something)".
• We are choosing among several ethical/moral nouns.

Concept/Approach
Qualm(s) = a feeling of uneasiness, doubt, or misgiving, especially about one's own conduct. The standard phrase is "to have no qualms about …".

Option analysis
qualms — correct idiom and meaning: "no qualms". ✅scruple — usually appears as plural "scruples" or in the set phrase "without scruple"; "no scruple" is less common.conscience — one has "no conscience" (as a character trait), but the idiom with an act uses "no qualms about".morals — plural noun; "no morals" is a general condemnation, not a momentary hesitation.

Usage note
Typical structure: "no qualms about + gerund/noun".

Final Answer
qualms