Which from following polymers is biodegradable?

Nylon 2-nylon 6 is the biodegradable polymer among the options.

While nylon 6 and nylon 6,6 are synthetic polyamides with poor biodegradability, and high-density polyethylene exhibits high resistance to degradation, nylon 2-nylon 6 is a copolymer of glycine and aminocaproic acid.

The amide linkages derived from these amino acids render it susceptible to enzymatic hydrolysis, enabling biodegradation.

The biodegradable polymer is therefore $\boxed{C}$.