Which component is often responsible for insufficient airflow in an electric heater system?

All of the options listed—worn out fan motor, clogged ducts, and dirty filters—can contribute to insufficient airflow in an electric heater system, which is why selecting "All of the above" is correct.

A worn-out fan motor may not be able to generate adequate airflow due to reduced power output or mechanical issues, directly impacting the efficiency of heat distribution in the system. Clogged ducts obstruct the flow of heated air, leading to uneven heating in different areas of a building. Dirty filters can restrict airflow as they accumulate dirt and debris, making it difficult for air to pass through and thus reducing the system's overall performance.

Since each of these components plays a crucial role in maintaining proper airflow, identifying and addressing any of these issues is essential for optimal operation of an electric heating system.