規範

会社の ___ に反する行為だ。

The correct answer is 規範 (きはん), meaning a norm, standard, or model of conduct. "会社の規範に反する行為" (an act that goes against the company's norms or standards of conduct) refers to behavior that violates the expected ethical or behavioral standards of the company. 規律 (きりつ) refers to discipline or a system of rules and order, focusing more on enforcement. 規則 (きそく) refers to specific, explicit rules or regulations. While an act could violate a specific rule, 規範 encompasses broader, often unwritten, ethical standards. 規約 (きやく) refers to a set of rules or an agreement, often in a contractual sense. 規範 is the most suitable for a general act that goes against the company's expected proper conduct.

正解は「規範（きはん）」です。「会社の規範に反する行為」は、会社における行動の模範や基準、倫理に背く行為を指します。これは明文化された規則だけでなく、暗黙の了解や倫理観も含む広い概念です。「規律（きりつ）」は行動を律する決まりや秩序、「規則（きそく）」は具体的なルール、「規約（きやく）」は組織や契約の取り決めです。「規範」は最も広範な「守るべき基準」を意味するため、文脈に最も適しています。