The answer is: b. recover and recycle refrigerant using EPA-approved equipment.
The Environmental Protection Agency (EPA) is an independent agency of the United States federal government for environmental protection.
EPA has approved the Air-Conditioning, Heating and Refrigeration Institute and Underwriters Laboratories to certify recycling and recovery equipment.
Standards are based on the Air-Conditioning, Heating and Refrigeration Institute (AHRI) 740 test protocol.