The answer is D because you want to have a control group! Hope it helps!
Answer:
Your skin goes through a natural turnover cycle every 30 days or so. When this happens, the upper layer of your skin (epidermis) sheds, revealing new skin from the middle layer of your skin (dermis). However, the cell turnover cycle isn't always so difinite.
hope this helps...
The correct answer is D aka Four i just took the test
Your general purpose as an advocate or leader<span> is to inform.</span>