下列选项中，不属于静态投资的是( )。

A．设备工器具购置费

B．建设单位管理费

C．建设期贷款利息

D．研究试验费

-- Do you know ________ her mobile phone? -- No, I think it cost her around 4000 yuan.

A．when your sister paid for

B．how much your sister will pay for

C．how much your sister paid for

D．when did your sister buy