About One-way streets, narrow single carriageways, separated carriageways and service roads: which statement is correct?

✓ The main road is intended for fast and through traffic, the ventweg for slow and local traffic (sign C5 at the entrance).
Sign C4 (blue rectangle, sideways arrow) obliges you to turn the way the arrow points at the junction.
If your right-hand wheels leave the road surface on a narrow single carriageway, you can simply steer calmly back to the middle.
If your right-hand wheels leave the asphalt, the only risk is damage to tyres or rims; the steering stays under control.

Correct answer: The main road is intended for fast and through traffic, the ventweg for slow and local traffic (sign C5 at the entrance).

Explanation

The main road is intended for fast and through traffic, the ventweg for slow and local traffic (sign C5 at the entrance)

C4 = one-way road: traffic in the SIDE STREET drives in the arrow's direction — a rectangular information sign about that street, not a command for your direction; commands are round (D series)
Watch out for a sharp edge and/or a lower-lying verge on narrow single carriageways outside the built-up area; if your right-hand wheels leave the road, you quickly lose control of your steering
On narrow single-carriageway roads outside the built-up area: watch out for a sharp road edge and/or lower verge; if your right-hand wheels leave the road, you quickly lose control of the steering