This question explores the different phases of the human hair growth cycle. Understanding these phases is crucial for comprehending how hair grows and renews.

Understanding the Hair Growth Cycle

The human hair follicle goes through a cyclical process of growth, transition, and rest. The primary phases are:

• Anagen Phase: This is the active growth phase where hair follicles produce new hair cells. The hair shaft is pushed upwards and grows longer. This phase can last for several years.
• Catagen Phase: This is a short transitional phase that marks the end of active growth. During this phase, the hair follicle shrinks, detaches from the dermal papilla, and the hair growth stops. It typically lasts about 2-3 weeks.
• Telogen Phase: This is the resting phase. The hair follicle remains inactive, and the hair strand stays in place, but no active growth occurs. This phase usually lasts for about 3 months. Towards the end of this phase, a new anagen phase begins, and the old hair strand is eventually shed.

Analyzing the Statements

Let's evaluate each statement based on the established understanding of the hair growth cycle:

Statement I: Anagen is a phase of active hair growth

This statement is correct. The Anagen phase is indeed the period of active growth for the hair follicle.

Statement II: Telogen is a transitional phase

This statement is incorrect. The Telogen phase is the resting phase, not a transitional one. The Catagen phase is the transitional phase that occurs between Anagen and Telogen.

Statement III: Catagen is a resting phase

This statement is incorrect. The Catagen phase is a brief transitional phase where the follicle stops growing and prepares for the resting period. The Telogen phase is the actual resting phase.

Conclusion on Hair Growth Phases

Based on the analysis, only statement I accurately describes a phase of the human hair growth cycle. Statements II and III incorrectly define the Telogen and Catagen phases, respectively.

Therefore, the only correct statement is I.