What type of engine is installed in this aircraft?

The correct answer describes a 4-cylinder engine that features opposed cylinders and is air-cooled. This type of engine is commonly used in light general aviation aircraft due to its balance between weight, simplicity, and performance. The opposed cylinder configuration helps in producing smoother engine operation and improved cooling efficiency, as the design allows for more uniform airflow across the engine's cylinders.

Having an air-cooled engine is beneficial for many smaller aircraft since it reduces complexity and weight compared to liquid-cooled systems, which require additional equipment and maintenance. In addition, air-cooled engines generally have fewer components that can fail, which adds to their reliability and lower maintenance requirements.

This design is prevalent in many popular training and recreational aircraft, making it a pertinent knowledge point for private pilots, as they are likely to encounter aircraft utilizing this type of engine in their training and future flying experiences.