_____ engaged in my present work,I would be quite willing to do what you ask me to.

___ A__ engaged in my present work,I would be quite willing to do what you ask me to.
A.Were I not B.Was I not
C.Would I not be D.Had I not been
此题应怎样选,为什么?---本题考查虚拟语气省略了if,应该用倒装,与现在相反的假设,用一般过去时.正常结构为：If I were engaged in my present work
还有,----如果我不是从事目前的工作,我将很乐意按你要求的去做.