General awareness of metallurgy is important to the welding inspector because:

A: Welding processes can affect both mechanical and corrosion properties of a weldment. B: The crystalline structure of base metals affects the resulting structure of the weld. C: Physical properties of the final weldment can be significantly affected by preheat and postweld heat treatment (PWHT). D: A thorough knowledge of weld metal structures is necessary to understand weldability.