Which vehicle components are typically checked during an emissions inspection?

The checking of vehicle components during an emissions inspection primarily focuses on parts that directly impact the vehicle's emissions output. Selecting the catalytic converter, oxygen sensors, and exhaust system as the components to check is correct because these parts play crucial roles in controlling and reducing harmful emissions from engine operations.

The catalytic converter is essential for converting harmful gases produced during combustion into less harmful substances before they exit the exhaust. Oxygen sensors monitor the level of oxygen in the exhaust and help optimize the air-fuel mixture, which is vital for efficient combustion and minimizing emissions. The exhaust system, which channels exhaust gases away from the engine, also has components that can become clogged or damaged, leading to increased emissions if not properly functioning.

In contrast, the other options involve components that do not directly correlate with emissions control. For instance, engine size and audio systems do not relate to emissions, and neither do brakes, tires, headlights, or turn signals, which are more relevant to vehicle safety and operation rather than emissions compliance. Hence, focusing on the specified components ensures that the vehicle adheres to emissions standards and contributes to a cleaner environment.