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
Microdermasion is done with: 
Select and explain. 
A. Aluminium oxide crystals, B. Aluminium trihydrate crystals, C. Ferrous oxide crystals, D. Ferric oxide crystals
A: Aluminium oxide crystals
Answer: A: Aluminium oxide crystals 
Explanation: Microdermabrasion is resurfacing technique with superficial skin wound achieved with aluminium oxide crystals. Ref: Textbook of dermatosurgery & cosmetology, Satish S savant, E-2, P-620.