This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Lactic acidosis is common in: 
Select and explain. 
A. Metformin, B. Phenformin, C. Repaglinide, D. Rosiglitazone
B: Phenformin
Answer: B: Phenformin 
Explanation: None