This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Which of the following factors tends to increase the lymph flow? 
Select and explain. 
A. Increased capillary hydrostatic pressure, B. Increase plasma oncotic pressure, C. Decreased capillary permeability, D. Precapillary constriction
A: Increased capillary hydrostatic pressure
Answer: A: Increased capillary hydrostatic pressure 
Explanation: The factor tend to increase lymph flow is increase in capillary hydrostatic pressure. Since the lymph is derived from the interstitial fluid, any factor that increases interstitial fluid pressure also increases lymph flow provided, the lymph vessel are functioning normally. The factors which increase interstitial fluid pressure include: Increased capillary hydrostatic pressure Increased interstitial fluid colloid osmotic pressure Increased permeability of the capillaries Decreased plasma colloid osmotic pressure All of the above factors increase the filtration at the capillary-interstitium interface and therefore increase the interstitial fluid volume and pressure. Ref: Guyton and Hall 13th edition Pgno: 200