When the road surface is wet, it is recommended to drive at 40 km/h.✓Correct answer
When the road surface is wet, it is recommended to drive at a maximum speed of 40 km/h.
Explanation
The 40 on a blue square is a recommended speed, and the rain plate makes that recommendation relevant when the road is wet. Calling it a maximum would confuse this advisory square with a red-bordered regulatory speed sign.
