The correct answer is 所属 (しょぞく). The verb 所属する (shozoku suru) specifically means 'to belong to' or 'to be affiliated with' a group, organization, or department. In a sentence like 『彼は営業部に所属している』(He belongs to the sales department), this word perfectly conveys that the person is an official member of that department within a company. Common Mistakes / Nuances: ❌ 付属 (ふぞく): 付属する (fuzoku suru) means 'to be attached to' or 'to be affiliated with'. However, its nuance is different. It is used for institutions or objects, implying a primary-secondary relationship, not for people as members of a team. For example, 『大学付属の高校』 (a high school affiliated with a university) or 『製品に付属するマニュアル』 (a manual that comes with a product). You wouldn't say a person is 'attached' to a department in this sense. ❌ 占有 (せんゆう): 占有する (senyuu suru) means 'to occupy exclusively' or 'to possess'. This word carries a strong sense of taking sole possession of a physical space, resource, or market. For example, 『公園のベンチを占有する』 (to occupy a park bench all by oneself) or 『市場を占有する』 (to monopolize a market). It does not fit the context of being a member of an organization. ❌ 専属 (せんぞく): 専属 (senzoku) means 'exclusive' or 'working under an exclusive contract'. While it denotes a form of belonging, it implies a special, binding contract where a professional works for only one client or company. It's used for roles like a 'personal lawyer' (専属の弁護士) or a 'model exclusive to a brand' (ブランド専属のモデル). A regular employee in a standard department is described with 所属, not 専属, as the relationship isn't typically one of contractual exclusivity in this specific sense.

正解は「所属（しょぞく）」です。動詞「所属する」は、ある団体や組織、部署の一員であることを的確に表す言葉です。例えば、「彼は営業部に所属している」という文では、彼が会社の一部門である営業部のメンバーであることを正しく伝えます。 Common Mistakes / Nuances: ❌ 付属 (ふぞく): 付属する (fuzoku suru) means 'to be attached to' or 'to be affiliated with'. However, its nuance is different. It is used for institutions or objects, implying a primary-secondary relationship, not for people as members of a team. For example, 『大学付属の高校』 (a high school affiliated with a university) or 『製品に付属するマニュアル』 (a manual that comes with a product). You wouldn't say a person is 'attached' to a department in this sense. ❌ 占有 (せんゆう): 占有する (senyuu suru) means 'to occupy exclusively' or 'to possess'. This word carries a strong sense of taking sole possession of a physical space, resource, or market. For example, 『公園のベンチを占有する』 (to occupy a park bench all by oneself) or 『市場を占有する』 (to monopolize a market). It does not fit the context of being a member of an organization. ❌ 専属 (せんぞく): 専属 (senzoku) means 'exclusive' or 'working under an exclusive contract'. While it denotes a form of belonging, it implies a special, binding contract where a professional works for only one client or company. It's used for roles like a 'personal lawyer' (専属の弁護士) or a 'model exclusive to a brand' (ブランド専属のモデル). A regular employee in a standard department is described with 所属, not 専属, as the relationship isn't typically one of contractual exclusivity in this specific sense.