This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
Which of the following characteristics make metformin a preferred biguanide than phenformin? 
Select and explain. 
A. It is more potent, B. It is less liable to cause lactic acidosis, C. It does not interfere with vitamin B12 absorption, D. It is not contraindicated in patients with kidney disease
B: It is less liable to cause lactic acidosis
Answer: B: It is less liable to cause lactic acidosis 
Explanation: (Ref: KDT 6/e p269) Incidence of lactic acidosis is more with phenformin and that of megaloblastc anemia (due to interference with vitamin B12 absorption) is more with metformin.