Arizona Commercial Air Conditioning Contractors are authorized to handle which type of cooling systems?

B is the correct response because Arizona Commercial Air Conditioning Contractors are specifically authorized to handle evaporative cooling systems as well as refrigeration systems. Evaporative cooling is a common practice in many areas of Arizona due to the dry climate, often providing energy-efficient cooling solutions. Refrigeration systems are critical for controlling temperatures in commercial applications, which includes everything from storing perishable goods to providing comfort cooling in larger environments.

The other options do not encompass the full range of systems that contractors are licensed to operate. The restricted type generally refers to more specialized systems that might require additional certification or training beyond the standard commercial license. Conventional cooling systems typically refer to standard air conditioning units, but limiting the scope of the contractor's authorization to only those systems would not reflect their capability to work within a broader range of technologies like evaporative cooling and refrigeration. Natural ventilation systems, while they are a component of HVAC, don’t involve mechanical systems that contractors are typically required to manage under their licensing.

Hence, the authorization provided to Arizona Commercial Air Conditioning Contractors is comprehensive enough to include both evaporative and refrigeration systems, making option B the most accurate choice.