What layer of skin contains the stem cells that cause fingernail growth

A nail grows from a deep layer of living epidermal tissues, called the nail matrix, at the proximal end of the nail. Stem cells in the nail matrix keep dividing to allow nail growth, forming first the nail root and then the nail plate as the nail continues to grow longer and emerges from the epidermis    

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nail matrix

Explanation:

it is found at the proximal end, and it contains stem cells, which form keratinocytes( which make up the nail)

1. is geographic distribution

2 is increasing complexity

3 is transitional forms