Which of the following should maintain the appropriate temperature and humidity levels and provide closed-loop recirculating: a. Air-conditioning, b. Positive pressurization c. Ventilation

If we define each of the systems that are given in the options we will have to:

Air conditioning is the air treatment that modifies its conditions to suit certain needs, i. e., the process of removing heat and moisture from the interior of an occupied space to improve the comfort of occupants. Air conditioners are also responsible for controlling humidity in closed rooms.

Positive Pressurization is a pressure within a system that is greater than the surrounding environment. Consequently, if there is any leakage of the system with positive pressure, it will leave the surrounding environment. There is no temperature or humidity control here

Ventilation is done by artificially creating depressions or overpressures in air distribution ducts or building areas. The fans are mechanically responsible for increasing the volume flow of air in a system. Moisture is not controlled directly.

Therefore the correct answer is A.