This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Conducting System of Hea, Subject name: Physiology
Which of the following segments of the circulatory system has the highest velocity of blood flow? 
Select and explain. 
A. Aoa, B. Aeries, C. Capillaries, D. Venules
A: Aoa
Answer: A: Aoa 
Explanation: The velocity of blood flow within each segment of the circulatory system is inversely propoional to the total cross-sectional area of the segment. Because the aoa has the smallest total cross-sectional area of all circulatory segments, it has the highest velocity of blood flow