Final answer:
Following a brief vasoconstriction, vasodilation is responsible for the increased blood flow and redness during acute inflammation, leading to localized congestion.
Step-by-step explanation:
The vascular, hemodynamic stage of acute inflammation is characterized by an initial brief period of vasoconstriction, followed by vasodilation, primarily mediated by substances like histamine. This vasodilation leads to increased diameter of capillaries, resulting in enhanced blood flow. Consequently, this process is responsible for the heat and redness observed in the inflamed area. Furthermore, vasodilation facilitates greater access of blood to the site of inflammation, ensuring that immune cells and other factors can reach and address the underlying cause of inflammation.
Simultaneously, the inflammatory mediators increase the vascular permeability, causing fluids to leak into the tissue spaces, leading to the swelling and edema that are typically associated with inflammation. Considering the effects of vasodilation and increased vascular permeability, the most accurate answer to the student's question is that vasodilation following initial vasoconstriction leads to localized congestion (B).