This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Normal transit time of keratinocytes is 
Select and explain. 
A. 3 weeks, B. 4 weeks, C. 5 weeks, D. 6 weeks
B: 4 weeks
Answer: B: 4 weeks 
Explanation: Transit time is the time required for the basal cells to reach uppermost part of epidermis,which is 4 weeks.It is decreased in psoriasis.