Final answer:
Club hair refers to hair in the telogen phase, which is the final stage of hair growth where the hair is at rest and about to be shed.
Step-by-step explanation:
The stage of hair growth during which the hair is known as club hair is the telogen phase. Hair growth occurs in three phases: the anagen phase, the catagen phase, and the telogen phase. The anagen phase is the period of active hair growth, and it can last for several years. The catagen phase is a transitional phase that lasts for about 2 to 3 weeks and marks the end of the active growing period. The telogen phase is the final stage, during which the hair follicle is at rest. This phase lasts for about 2 to 4 months, and at its end, the old hair is pushed out by a new hair starting the anagen phase again. Club hair refers to the state of the hair during the telogen phase when the hair has stopped growing and is about to be shed.