What type of system typically includes both heating and cooling components?

The correct choice is an HVAC system, which stands for Heating, Ventilation, and Air Conditioning. An HVAC system is specifically designed to control the indoor climate of a building by managing air quality, temperature, and humidity. This system integrates both heating and cooling components to provide comfort throughout the year, adapting to seasonal changes and occupant needs.

In contrast, a plumbing system focuses primarily on water supply and waste management, lacking the necessary components for heating or cooling air. A refrigeration system is primarily intended for cooling and preserving food or products, not for general climate control within a space. Meanwhile, a mechanical system is a broader term that can encompass various mechanical functions, but it does not inherently include both heating and cooling functionalities as part of its core design. Thus, the HVAC system stands out as the specialized system that includes both heating and cooling components, making it the correct choice.