The correct answer is **対象 (たいしょう)**. It perfectly captures the meaning of 'target,' 'object,' or 'subject' of an action, study, survey, or feeling. When we talk about the 'object of study,' we are referring to the thing upon which the action of studying is being performed, which is the exact definition of 対象. Common Mistakes / Nuances: ❌ : This is incorrect. Although it shares the same pronunciation, **対照** means 'contrast' or 'comparison'. It is used when you are highlighting the differences between two or more things. For example, 「AとBを対照する」 (to contrast A and B). This is a classic N2-level homophone trap that tests your kanji knowledge. ❌ : This is incorrect. **目標** means a 'goal' or 'objective' that one aims to achieve. It is a concrete, often measurable, endpoint you strive towards. For instance, 「今月の売上目標」 (this month's sales goal). The key difference is that a 目標 is something you aim *for*, while a 対象 is something you act *upon* (like studying or surveying it). ❌ : This is incorrect. **目的** means 'purpose' or 'aim'. It refers to the broader, underlying reason *why* you are doing something, which is often more abstract than a 目標. For example, 「日本に来た目的」 (the purpose for coming to Japan). While a study has a 目的 (purpose), the thing being studied is the 対象 (object/subject).

正解は **対象 (たいしょう)** です。「対象」は、ある行動、研究、調査、感情などが向けられる相手や物事を指します。「研究の対象」というように、何に焦点を当てて調べるかを示す場合にぴったりの言葉です。 Common Mistakes / Nuances: ❌ : This is incorrect. Although it shares the same pronunciation, **対照** means 'contrast' or 'comparison'. It is used when you are highlighting the differences between two or more things. For example, 「AとBを対照する」 (to contrast A and B). This is a classic N2-level homophone trap that tests your kanji knowledge. ❌ : This is incorrect. **目標** means a 'goal' or 'objective' that one aims to achieve. It is a concrete, often measurable, endpoint you strive towards. For instance, 「今月の売上目標」 (this month's sales goal). The key difference is that a 目標 is something you aim *for*, while a 対象 is something you act *upon* (like studying or surveying it). ❌ : This is incorrect. **目的** means 'purpose' or 'aim'. It refers to the broader, underlying reason *why* you are doing something, which is often more abstract than a 目標. For example, 「日本に来た目的」 (the purpose for coming to Japan). While a study has a 目的 (purpose), the thing being studied is the 対象 (object/subject).