I had to clear the spare room before I could start...

Câu hỏi: I had to clear the spare room before I could start decorating.

A Not until had I cleared the spare room I could start decorating.

B Before I cleared the spare room I could start decorating.

C Only when I had cleared the spare room could I start decorating.

D Only when I had finished clearing the spare room, I could start decorating.