Studies show that the things that contribute most to a sense of happiness cannot be bought, ________ a

good family life, friendship and work satisfaction.[ ]

A. as for  

B. in view of

C. in case of  

D. such as

某人手持边长为6 cm的正方形平面镜测量身后一棵树的高度．测量时保持镜面与地面垂直，镜子与眼睛的距离为0.4 m．在某位置时，他在镜中恰好能够看到整棵树的像；然后他向前走了6.0 m，发现用这个镜子长度的就能看到整棵树的像．这棵树的高度约为(　　)．

A．4.0 m

B．4.5 m

C．5.0 m

D．5.5m