💡 Detailed Explanation
Translation: I cleaned and made the room clean.
- Grammatical point: Adverbial form of na-adjective before する (to make ~).
- Explanation: To express making something have a certain quality (to clean / to make clean), use 'Na-adjective + に + する'. The na-adjective is きれい (clean/beautiful), so it becomes 'きれいにしました'.
- Other choices are incorrect inflections.