Cotton

The correct answer is option 1. Plastic.

Among the options provided, Plastic is non-biodegradable. Plastic is a synthetic polymer that does not easily break down or decompose naturally over time. Cotton and paper are biodegradable materials, as they can be broken down by microorganisms into simpler substances. Left-over food is also biodegradable, as it can decompose with the help of bacteria, fungi, and other microorganisms.