Which gases are commonly used in welding?

Oxygen and acetylene are widely used in oxy-acetylene welding, a common technique for joining metals. Oxygen supports combustion, while acetylene burns at high temperatures, enabling precise cutting and welding. This combination is effective for industrial applications. Options A, C, and D are incorrect, as oxygen and acetylene are the standard gases for this process, ensuring strong and efficient welds in various construction and repair tasks.