Blackheads differ from whiteheads because whiteheads are covered by skin, whereas blackheads are open to the air. What causes the dark coloration

Lipids within the sebum react with air, resulting in chemical oxidation and the formation of the black color.

Explanation:

This is the answer. I hope it helps you out.

a=c and then d= c because of the band so you get ac/dc and you add them together you get sound waves