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: Pathology
A most characteristic feature of acute in 
Select and explain. 
A. Vasoconstriction, B. Vascular stasis, C. Margination of leucocytes, D. Vasodilatation and increased vascular permeability
D: Vasodilatation and increased vascular permeability
Answer: D: Vasodilatation and increased vascular permeability 
Explanation: Acute inflammation has three major steps: -
Among these three major steps “The hallmark of acute inflammation is increased vascular permeability leading to escape of protein-rich fluid (exudates) into the extravascular tissue”.
Mechanism of increased vascular permeability
i. Formation of endothelial gaps in venules
ii. Direct endothelial injury resulting in endothelial cell necrosis and detachment.
iii. Delayed prolonged leakage
iv. Leucocyte mediated endothelial injury.