💡 Detailed Explanation
The word 'ふくざつ' (complicated/complex) is written in kanji as '複雑' (fukuzatsu). Sentence translation: 'This problem is complicated, so I don't understand it well.' The first character '複' means multiple/double, and '雑' means mixed/miscellaneous. The other choices use incorrect kanji combinations like '集' (to gather), '離' (to separate), and '難' (difficult) which do not form the word 'fukuzatsu'.