Why do guitars have different strings?

Answer: Thickness changes pitch produced

Each string plays one song — Wrong. Each string doesn't play a specific song. Strings produce different pitches that combine to play any music.

Strings wear out at different rates — Wrong. Strings do wear differently, but their main purpose is to produce different pitches through varied thickness and tension.

Thickness changes pitch produced ✓ — Correct! Guitar strings vary in thickness (gauge). Thicker strings vibrate more slowly, producing lower pitches, while thinner strings vibrate faster for higher pitches. Combined with different tensions, this creates the range of notes a guitar can play.