The runner directs the bouncing air back to the intake valve.

• A. Runner
• B. Plenum
• C. Throttle body
• D. Manifold

Answer: (A)

Air manages how it travels through the intake system in pulses. The path from the plenum to each cylinder is the runner, and that conduit is what directs the air—and the pressure waves it carries—toward the intake valve. When the valve opens and closes, those pressure waves travel up the runner and can reflect back toward the valve, helping to push more air into the cylinder at the right moment. That resonance effect is what the runner is responsible for.

The plenum acts as a larger reservoir to smooth out those pulses, the throttle body controls how much air enters, and the manifold is the whole assembly that includes both the plenum and the runners. But the specific channel that guides air to the valve and supports that reflective action is the runner, which is why it’s the best answer.