This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Circulation, Subject name: Physiology
Which of the following ors filtration at the aeriolar end of the capillary bed? 
Select and explain. 
A. Decrease in hydrostatic pressure of capillaries, B. Increase in hydrostatic pressure of capillaries, C. Increase in oncotic pressure of capillaries, D. Decrease in oncotic pressure of interstitium
B: Increase in hydrostatic pressure of capillaries
Answer: B: Increase in hydrostatic pressure of capillaries 
Explanation: Starling's forces: The forces acting on the capillary to cause movement of fluid into or out of the capillary. Two forces that tend to move the fluid out of the capillary - Capillary hydrostatic pressure Interstitial colloid oncotic pressure. Two forces that tend to move the fluid back into the capillary - Plasma colloid oncotic pressure Interstitial hydrostatic pressure. At the aeriolar end of the capillary: The balance or net sum of these forces or the fluid to move out; thus fluid leaks out of the capillary at this end. At the venous end of the capillary: The balance or net sum of these forces is in the or of fluid movement back into the capillary.