Final answer:
Ridges running vertically down the natural nail plate are typically caused by d. genetic factors and are a normal sign of aging. Nails are mainly composed of keratin and grow from the nail matrix.
Step-by-step explanation:
Ridges running vertically down the natural nail plate are caused by d. genetic factors. These ridges are often a normal sign of aging and are not usually a cause for concern.
However, in some cases, they can indicate a nutritional deficiency or a health problem. It's important to have a professional look at your nails if you are concerned about the ridges.
Nails are composed mainly of a protein called keratin. This protein is also found in the skin and hair. The nail grows from the nail matrix, a deep layer of living epidermal tissues at the proximal end of the nail.
The nail bed lies beneath the nail plate and contains capillaries that give it a pink color due to the blood flow.