Question

which of these is a polymer?
a strand of dna
a single carbon atom

Explanation:

A polymer is a large molecule made of repeating subunits (monomers). DNA is a polymer where the monomer is a nucleotide. A single carbon atom is an atom, not a polymer. A strand of DNA is made of many nucleotide monomers linked together, so it is a polymer.

Answer:

a strand of DNA