Final answer:
The correct answer to the question is c. Tack welding, which involves placing a small weld at each end of a joint to keep it in position during the welding process.
Step-by-step explanation:
Placing a small weld at each end of a joint to keep it in place during welding is known as tack welding. The main purpose of tack welding is to maintain the alignment of the pieces as they are being fully welded.
Bead welding refers to laying a bead of weld along a seam. Fillet welding is the process of joining two pieces of metal at a right angle or an angle less than 180 degrees. Groove welding involves placing a weld in the groove between two pieces of metal.
Therefore, the correct answer is c. Tack welding.