集体谈判的特征，是谈判问题的特殊复杂性和()。

A.特殊性

B.多变性

C.艰难性

D.不确定性

.On Feb 27, Chinese Premier Wen Jiabao took part in _____ online chat with Chinese netizens, who expressed interests and concerns over property prices, inflation, ________ wealth gap and other social issues.

A．the ; a

B．an ; /

C．the; the

D．an ; the