Answer:
pretty sure its A hope this helps!
DNA is an example of a complex biological polymer called a nuclei acid. Nucleic acids are made up of many smaller sub units called nucleotides. The components of a DNA nucleotide are deoxyribose, phosphate group, nitrogen group. There are four possible bases in a DNA molecules which includes adenine, cytosine, guanine and tymine.
A. Shellfish will disappear first if an estuary was destroyed.
Answer:
I believe it is A.
Explanation:
Im not 100% sure though so I'm so sorry if it's wrong.