This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
In severe exercise, decrease in pH is due to: 
Select and explain. 
A. Respiratory acidosis, B. Lactic acidosis, C. H+ retention, D. HCO3 excretion
B: Lactic acidosis
Answer: B: Lactic acidosis 
Explanation: Ans. (b) Lactic acidosis(Ref: Guyton, 13th ed/p.1085)Accumulation of lactic acid causes decrease in pH, muscle cramps and muscle fatigue,