Final answer:
The correct answer to the question is A) additional, as some welding processes use external filler material to reinforce or fill the joint being welded.
Step-by-step explanation:
Some welds use just the local material to make the joint, others use additional material. The correct answer is option A) additional. In welding, when only the base metals are melted to form the joint, it is referred to as autogenous welding.
However, to strengthen the weld or fill gaps, external material, which can be welding rod, wire, or electrodes, is often added to the weld pool. This material is known as filler material and is used to ensure that the joint has the requisite mechanical properties, such as strength and ductility.