The incorrect statement among the given options is [B] Both air conditioner and air cooler control humidity. Air conditioners are designed to control both the temperature and humidity levels in a room. They work by removing heat and moisture from the air, thus lowering both the temperature and humidity. On the other hand, air coolers operate using the principle of evaporative cooling, which involves blowing air through water-soaked pads. This process adds moisture to the air, thereby not controlling but actually increasing humidity.

While air conditioners effectively manage and reduce humidity, air coolers can make the air more humid, especially in already humid environments. Therefore, the statement that both air conditioners and air coolers control humidity is incorrect. Thus, [B] is the incorrect statement, as air coolers do not have the capability to control or reduce humidity levels effectively.