When changing lanes, adriver should use his turning signal to let other drivers know ______     [ ]

A. he is entering which lane      

B. which lane he is entering      

C. is he entering which lane      

D. which lane is he entering

（　　）反映证券或组合对市场变化的敏感性。

A．β系数

B．标准差

C．市盈率

D．市净率