The driver turned his car sharply to the left to give the way to the running bull only _________ a tree by the road.                                                   

A．to knock into

B．knocking down

C．to knock at

D．knocked over

根据我国《保险法》的规定，保险人委托保险代理人代为办理保险业务的，应当与保险代理人签订委托代理协议，依法约定双方的权利和义务及其他代理事项。