Final answer:
The tissue responsible for generating the cells that become the nail as they harden and move outward is the nail matrix, not the eponychium, nail fold, or nail plate. Therefore, the correct option is 2.
Step-by-step explanation:
The active tissue that generates cells which harden as they move outward from the root to the nail is called the nail matrix. The nail matrix is a deep layer of living epidermal tissue located at the proximal end of the nail. Stem cells within the nail matrix actively divide, forming keratinocytes, which are cells that produce keratin and eventually become part of the nail plate.
The three main parts of a nail are the nail root, nail plate, and free margin. The process of nail growth begins in the nail root, with the nail plate being the actual visible, hardened part of the nail. As the cells grow and become keratinized, they form the nail plate that slides over the nail bed, creating the appearance we recognize as our nails.
The nail matrix is essential for the continuous growth of the nail, and it should not be confused with the eponychium (also known as the cuticle), the nail fold, or the nail plate itself. It is this proliferation of cells in the nail matrix which contributes to the nail's length and maintenance of its health and structure.