How do base metal thickness and joint design influence heat input and the number of passes required in GTAW?

• A. Thicker metal requires lower heat input.
• B. Thicker metal and looser joints require fewer passes.
• C. Thinner metals and tighter joints require lower heat input and fewer passes; thicker sections may require higher heat input and multiple passes.
• D. Joint design has no effect.

Answer: (C)