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: Skin
Which of the following is an agent used for deep chemical peels? 
Select and explain. 
A. Carbolic acid, B. Glycolic acid, C. Mandelic acid, D. Salicylic acid
A: Carbolic acid
Answer: A: Carbolic acid 
Explanation: Carbolic acid / phenol is used for deep peels & is a component of Baker - Gordon formula. All others are hydroxy acids used for superficial & medium depth peels. Ref: Textbook of dermatosurgery & cosmetology, Satish S savant, E-2, P-177.