D.to do; interested in
Many boys and girls are made to do what they're not interested in
整个句子是个宾语从句.主句是个被动语态.被动语态时,to不能省略.to do 只是make的宾语补足语.what ...后面的全是make的宾语,英语语法中规定,宾语从句中,从句必须是陈述句语序即:...what they are not interested in
interesting :adj.令人感兴趣的.一般用来修饰物或以物作为主语.一般情况下,动词的现在分词结构即：V.+ing 做形容词时都译为：令人...的.interested :adj.感兴趣的.一般人作主语.be interested in :是个固定搭配,译为：对...感兴趣.