Final answer:
Servicing an AC welding machine requires a professional due to the high voltage. Among the given choices, a qualified electrician is the correct professional to perform such service. They have the necessary training and certification to handle electrical systems safely.
Step-by-step explanation:
When dealing with an AC welding machine, which is a complex and potentially dangerous device, it's crucial to have a professional handle its servicing due to the high voltage involved. Considering the options provided, the correct answer is d. Qualified electrician.
An AC welding machine is essentially a generator powered by electricity and it converts other sources of power into electrical. Given the risks associated with electrical systems, which can include electric shock, burns, or even worse, it is not a job for a mechanic, welder, or supervisor if they are not specifically trained for it.
It's essential that anyone servicing highly technical and energized equipment such as an AC welding machine should have the appropriate training, certifications, and knowledge in electrical systems.