What are the functions of anti-freeze in the coolant system?

The selected combination is correct because anti-freeze performs two essential functions in the coolant system: it protects against corrosion and prevents the cooling system from freezing.

1. **Protection against corrosion**: Anti-freeze contains additives that prevent rust and corrosion within the engine and the coolant system. This is crucial for maintaining the longevity and efficiency of the vehicle, as corrosion can lead to leaks and mechanical failures.

2. **Protection against freezing**: In colder climates, anti-freeze lowers the freezing point of the coolant. This is important to ensure that the coolant remains fluid and effective even in low temperatures, preventing damage to the engine.

Both of these functions are vital for vehicle safety and performance, which are emphasized in German traffic regulations. Proper maintenance of the coolant system helps prevent breakdowns and ensures the vehicle operates safely under different weather conditions.