A behavioral or physical adaptation is something ___ helps a species survive
makes a species prettier to look at
makes a species become extinct
prevents a species from surviving

Explanation:

The answer is

helps a species survive

chromosomes carry the genetic information for organisms. also, chromatin is the thread like dna which is located in the nucleus of an organism.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.