The ADG powers ________.

The ADG, or Automatic Deployment Generator, is designed to provide emergency electrical power to critical systems when the main power sources fail. When considering the systems powered by the ADG, it indeed has the capability to supply electricity to emergency lighting, environmental control systems, and primary flight instruments.

Emergency lighting is essential for passenger safety and evacuations during a loss of power. The environmental control systems, which manage cabin temperature and air quality, are vital for passenger comfort and aircraft operational integrity. Additionally, primary flight instruments, which provide critical information to pilots about the aircraft's status, rely on electrical power to function, ensuring that the pilots can maintain control of the aircraft in emergency situations.

Thus, since the ADG can provide power to all these essential systems, the correct answer embraces the comprehensive functionality of the ADG in terms of supporting critical operations during emergencies.