What should you be prepared for here?

Your answer is fully correct. In rainy conditions shown here, German traffic rules emphasize two main points:

1. Extended braking distance is necessary because wet roads reduce tire grip, making it harder to stop quickly. Drivers should increase their following distance and brake earlier to avoid accidents.

2. Poor visibility of your vehicle means other drivers may find it harder to see your car due to rain and spray from the road. Using headlights appropriately improves your visibility to others.

Tyre traction is actually reduced, not increased, in wet conditions, so option 3 is incorrect. Remembering to adjust speed, braking distance, and visibility aids ensures safer driving in rain.