Who is permitted to sell refrigerants?

The ability to sell refrigerants is restricted to ensure that only qualified individuals handle these chemicals, which can be harmful to the environment and require proper knowledge for safe handling. Technicians who are EPA certified in refrigerant recovery have demonstrated that they understand the regulations and best practices concerning refrigerants. This certification indicates that these individuals have received proper training, which includes knowledge about the safe use, disposal, and recovery of refrigerants.

In contrast, the other options do not ensure the same level of competence. A valid driver's license does not equate to understanding refrigerant handling, and while licensed contractors may have the necessary training, the requirement is specifically related to certification in refrigerant recovery. Attending a refresher course may enhance knowledge but does not alone qualify someone to sell refrigerants without the required EPA certification. Therefore, the correct choice emphasizes the necessity of having the appropriate EPA certification to legally sell refrigerants.