Final answer:
An improperly made restart in GMAW or FCAW welding processes is most commonly associated with porosity, which is the formation of small holes or voids caused by trapped gas. So option (B) is correct.
Step-by-step explanation:
An improperly made GMAW (Gas Metal Arc Welding) or FCAW (Flux-Cored Arc Welding) restart could potentially lead to several types of defects in the weld. However, the most common issue associated with a poor restart in these welding processes is porosity.
Porosity is the presence of tiny holes or voids within the weld metal, which are created by trapped gas. This is because, during an improper restart, the shielding gas may not protect the molten weld pool adequately, allowing atmospheric gases to contaminate the pool and become trapped within the solidifying metal. Inclusion, on the other hand, refers to non-metallic materials trapped within the weld, while crack is a fracture or discontinuity that develops in the metal. Burn-through is when excessive heat melts through the metal being welded.