Which component allows the operator to adjust the airflow signal for optimum combustion?

The correct answer is the fuel air ratio relay. This component is essential in combustion systems because it helps maintain the correct balance of fuel and air in the combustion process. Adjusting the airflow signal is crucial for optimizing combustion efficiency, reducing emissions, and ensuring the safe operation of the system.

The fuel air ratio relay works by measuring the concentrations of fuel and air and then adjusting airflow accordingly to achieve the optimal mixture. This adjustment is vital because an improper fuel-to-air ratio can lead to inefficient combustion, resulting in wasted fuel, increased emissions, and possible damage to the equipment.

In contrast, control pressure typically relates to the overall system pressure and does not directly adjust airflow for combustion. The minimum signal selector usually pertains to selecting the minimum signal needed from various sensors and is not focused specifically on airflow for combustion optimization. The steam flow rate relay monitors steam production and does not influence the air-fuel mixture in combustion processes.