下列食物链需要能量最多的是[ ]

A．草→兔→鹰        

B．草→兔→狗→人

C．小麦→蝗虫→鸡   

D．小麦→蝗虫

“Everyone thinks of changing the world, _______ no one thinks of changing himself.” A famous Russian writer once said.

A．so

B．because

C．and

D．but