以下影响供需的主要因素中，影响房地产周期循环的最关键的因素是( )。

A．房地产价格
B．房地产市场预期
C．金融相关因素
D．相关商品价格

—Would you like to go hiking with us this Sunday?

—I'd like to, but I'll have _______ to do. [ ]

A. special something

B. something special

C. anything special

D. special anything