Air path into the engine — correct intake order Select the correct order in which intake air flows into a typical spark-ignition engine (carburettor or throttle body system).

Introduction / Context:
Air induction affects filtration, metering, and mixture formation. Service technicians must know the correct order of components to troubleshoot restrictions and leaks, and to route sensors properly in both carburetted and throttle-body-injected systems.

Given Data / Assumptions:

• Passenger car spark-ignition engine.
• Air is filtered before fuel metering or throttle control.
• Intake manifold distributes air-fuel or air to individual intake ports.

Concept / Approach:
The air cleaner is first to remove dust. Next, a carburettor or throttle body meters fuel and controls air. The intake manifold then distributes the flow to cylinders via cylinder head intake ports. Therefore, the correct sequence begins with filtration and ends in the combustion chambers.

Step-by-Step Solution:
Place air cleaner at the inlet to prevent debris ingestion.Follow with the metering/controlling device: carburettor or throttle body.Route through intake manifold runners.Enter intake ports and then cylinders.

Verification / Alternative check:
Visual inspection under most hoods confirms the sequence: airbox and filter upstream, throttle body, then manifold, then head ports.

Why Other Options Are Wrong:
Options a and c place components in impossible or illogical sequences. Option b swaps ports and manifold order; ports are within the head and follow the manifold.

Common Pitfalls:
Confusing port injection (injectors at ports) with throttle-body injection; the airflow path order does not change.

Final Answer:
air cleaner -> carburettor (or throttle body) -> intake manifold -> intake ports -> cylinders