Final answer:
The standard measure of airflow across an air-conditioning coil is CFM (Cubic Feet per Minute).
Step-by-step explanation:
The standard measure of airflow across an air-conditioning coil is CFM (Cubic Feet per Minute). CFM represents the volume of air that passes through the coil in one minute. It is a commonly used unit to measure airflow in HVAC (Heating, Ventilation, and Air Conditioning) systems.
For example, if an air conditioning system has a CFM rating of 500, it means that 500 cubic feet of air pass through the air-conditioning coil every minute.
Other options mentioned in the question, such as refrigerant pressure, evaporator coil temperature, and air velocity, are factors that can affect the airflow across the coil, but they are not the standard measure of airflow itself.