The following picture contains several road elements. How should a driver respond when approaching these elements?

1. A Slow down and keep to the right.
2. B He should make a warning honk, continue driving in normal speed, glance at the mirrors and then drive faster to quickly cross the curve.
3. C Approaching a curve in high speed is dangerous on a rough road only.
4. D In the absence of a road sign warning about an incoming curve, there is no need to slow down. He should continue driving at normal speed.