You are really very kind.I'll never forget the ______ you have done to me. [ ]

A. favour  

B. deed  

C. help  

D. kind

哪种先心病可发生差异性紫绀

A．动脉导管未闭

B．房间隔缺损

C．肺动脉瓣狭窄

D．法洛四联症

E．室间隔缺损