A multi-zone, constant volume, variable temperature system is defined by which of the following features?

A multi-zone, constant volume, variable temperature system is defined by the features of having both a hot deck and a cold deck. In HVAC systems, the term "hot deck" refers to the area or zone where heated air is distributed, while the "cold deck" is where cooler air is supplied. This setup allows different zones within a building to maintain varying temperatures based on their specific heating and cooling needs while maintaining a consistent volume of air distribute.

This type of system is designed to manage temperature fluctuations across different areas by controlling the distribution of air. The presence of separate decks allows for the flexibility needed to cater to different zones within a structure, making it efficient for temperature management in larger or multi-zone buildings.

In contrast to single zone control, which focuses on maintaining a single temperature for a whole area, or variable volume systems that adjust airflow permanently, the hot and cold deck design allows for a structured way to control multiple environments at different temperatures effectively.