During which phase do lashes exist for the shortest period of time?

The phase during which lashes exist for the shortest period of time is the catagen phase. This phase marks a transitional period in the hair growth cycle, where the hair follicle shrinks, and the hair separates from its nourishing blood supply. The catagen phase typically lasts just a few weeks, making it significantly shorter compared to the other phases.

In contrast, during the anagen phase, which is the active growth stage, lashes can remain for several months as they are developing and growing. The telogen phase is the resting phase where lashes remain in a dormant state for a significant period before shedding, while the exogen phase refers to the shedding of the hair, which follows the telogen phase and can also last a while as old hairs are released. Thus, the catagen phase is characterized by its brevity, making it the correct answer regarding the shortest duration of lash existence within the hair growth cycle.