The lower part of the hair root is the club-shaped

• A. Hair Bulb
• B. Arrector Pili
• C. Hair Root
• D. Medulla

Answer: (A)

The lower part of the hair root is club-shaped because that portion is the hair bulb, the rounded enlargement at the base of the follicle where hair growth occurs. The hair bulb houses the hair matrix, where living cells divide to form new hair, and it connects to the dermal papilla that provides nutrients and signals for growth. This bulb-like structure gives the lower end of the root its characteristic club shape.

The other structures are not the club-shaped part: the arrector pili is a tiny muscle attached to the follicle that makes hair stand on end, not part of the growth zone; the medulla is the innermost layer of the hair shaft, located inside the hair rather than at the base; and the hair root refers to the portion below the skin, which includes the bulb but isn’t specifically defined by that club-shaped enlargement.