What is the lifespan of the average hair?
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1 year
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5 years
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10 years
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20 years
B
Correct answer
Explanation
The active growth phase (anagen) of a hair follicle typically lasts between 2 to 7 years, making 5 years a representative average lifespan for a single hair. After this phase, the hair enters resting and shedding phases before a new one grows.