Which of the following does the firewall shutoff handle cut off to the engine?

The shutdown mechanism referred to as the firewall shutoff handle is crucial in controlling the flow of necessary fluids and air to the engine. When this handle is engaged, it effectively interrupts the supply of fuel and hydraulic fluid.

Fuel is essential for combustion, and hydraulic fluid is critical for operating various systems, including flight controls and landing gear. Interrupting these supplies ensures that the engine can be safely shut down in emergency situations or during maintenance, thereby preventing potential hazards associated with uncontrolled fuel flow or hydraulic pressure.

The other options, while they mention important aspects of engine operation, do not accurately represent the primary functions of the firewall shutoff handle. For example, air pressure and bleed air relate primarily to air delivery systems supporting engine performance, and electrical power is managed by separate systems in aircraft, making them less relevant to the specific function of the firewall shutoff handle in this context.