Failure of which component may result in a high level of hydrocarbon emissions?

The fuel injectors are critical components in controlling the precise amount of fuel that is delivered to the engine's intake manifold. When fuel injectors fail or become clogged, they may not deliver enough fuel or may deliver too much fuel into the combustion chamber. This mismanagement of fuel can lead to incomplete combustion, which in turn produces a higher level of hydrocarbons in the exhaust emissions. Hydrocarbons result from unburned fuel being released during the combustion process, indicating that the engine is not operating efficiently.

The throttle body, while important for regulating airflow into the engine, primarily influences air intake rather than directly affecting fuel delivery. The starter motor and alternator are critical for starting the vehicle and powering electrical systems, but they do not play a significant role in the combustion process or in the management of fuel and emissions. Hence, failures here would not directly lead to increased hydrocarbon emissions.