I don't like to be disturbed if I_____A.work B.will work C.am working D.have worked老师说选C,为什么?

I don't like to be disturbed if I_____A.work B.will work C.am working D.have worked老师说选C,为什么?
I don't like to be disturbed if I_____
A.work B.will work C.am working D.have worked
老师说选C,为什么?

I don't like to be disturbed if I_____A.work B.will work C.am working D.have worked老师说选C,为什么?
根据句子的意思：当我（）的时候,我不喜欢被人打扰.所以,这里应该填当我“正在工作”的时候,因此选C.