💡 Detailed Explanation
The correct choice is 'やすい' (forming '使いやすい' - easy to use). The grammar pattern '[Verb Stem] + やすい' means that something is easy or comfortable to perform. Given '軽くて' (lightweight), it logically leads to being easy to use. Sentence translation: 'These scissors are lightweight and very easy to use.' 'にくい' means difficult to use.