Explanation:

- Option 1: Copper

- Not typically used in LED technology for the semiconductor itself.

- Commonly used in wiring due to its excellent electrical conductivity.

- Option 2: Gallium

- Used in LED technology, specifically in gallium arsenide (GaAs) and gallium nitride (GaN) semiconductors.

- These compounds facilitate efficient light emission.

- Option 3: Iron

- Not used in LED semiconductor technology.

- Commonly used in construction and manufacturing due to its strength and magnetic properties.

- Option 4: Zinc

- Not a primary material for LED semiconductors.

- Often used in alloys and to galvanize steel for corrosion resistance.