Which of the following best describes the role of environmental control systems during flight?

The role of environmental control systems during flight is primarily focused on ensuring passenger comfort. These systems maintain a suitable cabin environment by regulating temperature, humidity, and air quality. They work to provide fresh air circulation and remove contaminants, which is essential for long-duration flights and high altitudes where the outside atmosphere can be extreme. A comfortable environment improves the overall flying experience for passengers and contributes to their well-being during a flight. While other functions, such as providing emergency oxygen, play a crucial role during specific situations, the overarching aim of the environmental control systems throughout the flight is to create a pleasant and safe atmosphere for passengers.