HVAC meaning

In the context of real estate, what does HVAC stand for?

  1.  Housing, Ventilation, Architecture, and Control
  2.  Homeguard, Vacuuming, Airing, and Cost
  3. Heating, Ventilating, and Air Conditioning
  4.  Homogenous, Valuation, Actuarial, Collective

Explanation:

The answer is C. HVAC stands for Heating, Ventilating, and Air Conditioning.  All of the other options are fictitious.