Can some help me Is the Vitamin D that our skin makes when exposed to the sun's rays natural or synthetic? Why might it be useful for scientists to synthesize a compound that can be found in nature?

D from the sun is synthetic.

"Chemists synthesize chemical compounds that occur in nature in order to gain a better understanding of their structures."

Explanation:

"Chemists synthesize chemical compounds that occur in nature in order to gain a better understanding of their structures. Synthesis also enables chemists to produce compounds that do not form naturally for research purposes. ... Each step usually involves reaction at only one chemical bond in the molecule."

Credit to www.britannica.com