Final answer:
A healthy adult typically loses 50-100 hairs a day, which aligns with answer choice A) 50-100 hairs. This loss occurs naturally as part of the hair growth cycle with its three phases: anagen, catagen, and telogen.
Step-by-step explanation:
In healthy adults, about A)50-100 hairs are lost a day.
This is a natural part of the hair growth cycle, which occurs in three phases: the anagen phase, the catagen phase, and the telogen phase.
During the anagen phase, which can last for 2 to 7 years, hair grows actively.
The hair then transitions during the catagen phase, a period of 2 to 3 weeks when growth ceases.
Finally, hair enters the telogen phase, a resting period lasting about 2 to 4 months.
After this phase, the cycle starts again with the anagen phase, producing new hair to replace the one that is shed.
Hair loss greater than this average rate can be caused by hormonal or dietary changes, aging, or the influence of hormones.
Furthermore, the evolution of human beings has shown that we lost most of our body hair about a million years ago, likely for reasons of thermoregulation and parasite control.