💡 Detailed Explanation
Translation: Mr. Tanaka can write 100 kanji.
- Grammatical point: Potential ability pattern '〜ことができる' (can do ~).
- Explanation: The pattern requires the dictionary form (辞書形) of the verb before 'こと'. The verb is 書く (かく - to write), so 'かく' is correct.
- Other options are not dictionary forms.