Final answer:
The statement regarding the free edge of the nail plate is true. The free margin is the part of the nail extending over the digit's tip, and nails are mainly composed of a protein known as keratin.
Step-by-step explanation:
The statement 'The free edge is the part of the nail plate that extends over the tip of the finger or toe' is true. The free margin, also called the free edge, is indeed the portion of the nail that extends past the distal end of the finger or toe, not involved in direct growth but essential for protection.
The nail bed lies beneath the nail plate and is a specialized epidermal structure at the fingertip enriched with blood vessels, responsible for the pink appearance of the nails, except at the lunula. The nail plate is the hard part of the nail, made of densely packed dead keratinocytes, which is the main protein nails are composed of.
Nails are primarily composed of a protein called keratin, which is instrumental in providing the strength and rigidity required for the protective functions of nails. This keratinous structure is formed at the nail root and grows continuously thanks to proliferating cells in the nail matrix.