Answer:
D. The nervous System. Hope it Works
Explanation:
DNA<span> structure. </span>DNA is made<span> up of </span>molecules<span> called </span>nucleotides<span>. Each </span>nucleotide<span>contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).</span>