Soldering is the process in which two or more items are joined together by melting and putting a filler metal into the joint.

• A. The process in which two or more items are joined together by melting and putting a filler metal into the joint.
• B. The act of heating metals to fuse them without filler metal.
• C. Removing solder and components from a circuit board.
• D. A flux used in soldering.

Answer: (A)

Soldering is the act of joining parts by melting a filler metal and letting it flow into the joint. This filler metal, solder, has a lower melting point than the pieces being joined, so the base metals stay solid while the solder melts and fills gaps, often with flux helping clean surfaces and promote wetting. The description matches this process exactly: two or more items are joined by melting and introducing a filler metal into the joint.

The other statements describe related ideas but not the process itself: heating metals to fuse them without filler metal describes welding; removing solder and components is desoldering; a flux is a chemical used to aid soldering, not the process.