Who is correct about the functions a test only station technician can perform?

The correct choice highlights that a test-only station technician must operate under certain regulatory guidelines, which dictate that a licensed technician must be employed at the facility. This ensures that the testing process is conducted by someone who is appropriately trained and knowledgeable about the specifications and procedures related to emissions testing.

Test-only stations have specific limitations on the types of repairs they can perform to maintain the integrity of the testing process. The primary focus is on evaluating emissions without the potential conflicts of interest that may arise if technicians are allowed to perform repairs that could influence test outcomes. Because of this regulation, it's mandatory to have a licensed technician present to oversee operations and ensure compliance.

In contrast, the other technician's statement about replacing a gas cap reflects a misunderstanding of the regulations governing test-only stations. Such operations typically fall outside the scope of what these facilities are permitted to do, emphasizing the importance of technician B's position in maintaining adherence to industry standards.