Final answer:
Pulling the firewall shutoff handle in a vehicle cuts off the flow of fuel to the engine and stops it from running.
Step-by-step explanation:
Pulling the firewall shutoff handle in a vehicle helps to cut off the flow of fuel to the engine, which stops the engine from running. The firewall in a vehicle separates the engine compartment from the passenger compartment and contains various components, including the fuel line. By pulling the shutoff handle, you can stop the flow of fuel and effectively shut down the engine.