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
Most important factor in rapid progression of Bacteria resulting in pulpal necrosis is? 
Select and explain. 
A. Host resistance, B. Virulence of bacteria, C. Dentinal Fluid flow, D. Pulp vitality
D: Pulp vitality
Answer: D: Pulp vitality 
Explanation: None