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
Which of the following is not a component of cell rich zone 
Select and explain. 
A. Collagen Type 1, B. Collagen type 3, C. Collagen type 5, D. Stem cells
C: Collagen type 5
Answer: C: Collagen type 5 
Explanation: Collagen fibers type 1 and type 3 are present in cell rich zone while type 5 is absent.