Which of the following symptoms indicates an issue with a heating system's air flow?

Choosing the option that indicates "All of the above" is correct because each of the symptoms listed can indeed signal airflow issues within a heating system.

Noisy ducts can suggest that there is an obstruction or restriction in the airflow, causing pressure to build up, which results in rattling or banging noises. This indicates that the air is struggling to move freely through the ductwork, pointing to potential blockages or inadequate sizing of ducts.

Cold spots in rooms are a clear indicator of insufficient airflow. If specific areas in a home are not receiving adequate heat, it suggests that the airflow is compromised, possibly due to duct design, constraints, or issues with the heating unit itself. The heat distribution may not be even, demonstrating further problems with movement of the heated air.

Long heating cycles imply that the system is running longer than normal to reach the desired temperature. This can occur when airflow is restricted, making it difficult for the system to deliver sufficient heated air to satisfy the thermostat demands. As a result, this extended operation can lead to increased energy consumption and wear on the heating system.

Each of these indicators points towards a limitation or malfunction concerning airflow, affirming that all presented options collectively highlight symptoms linked to airflow issues in a heating system.