The **cooling systems** in a vehicle are essential to keep the engine at an appropriate temperature and prevent it from overheating. There are two main types of cooling systems:

1. **Air cooling**: This system uses the air circulating around the engine to dissipate heat. It is more common in small engines or older vehicles.

2. **Liquid cooling**: In this system, a **coolant** circulates through the engine, absorbing the generated heat. Then, this liquid is cooled in the **radiator** before returning to the engine, driven by a **water pump**. It is important to maintain the proper level of coolant and ensure that the belts and cooling circuit are in good condition for optimal operation.


Therefore, the two types of cooling systems that exist in an engine are **air and liquid**, which makes the correct answer option 1.