问题
_____, the car stopped all at once.
A:Seeing a boy lying on the ground
B:On seeing a boy sitting on the road
C:The driver saw a boy standing on the road
D:The minute the driver saw a boy seated on the road
B:On seeing a boy sitting on the road
C:The driver saw a boy standing on the road
D:The minute the driver saw a boy seated on the road
正确答案是：
