This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammation, Subject name: Pathology
A 34-year-old man presents with a 5-day history of a painful sore on his hand. Physical examination reveals a 0.5-cm abscess on the extensor surface of the left hand that drains a thick, purulent material. Diapedesis of leukocytes into and around this patient's infected wound occurs primarily at which of the following anatomic locations? 
Select and explain. 
A. Lymphatic capillaries, B. Postcapillary venules, C. Precapillary aerioles, D. Small dermal aeries
B: Postcapillary venules
Answer: B: Postcapillary venules 
Explanation: One of the earliest responses following tissue injury occurs within the microvasculature at the level of the capillary and postcapillary venule.