This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
What is the mechanism by which the following technique works? 
Select and explain. 
A. Cryotherapy, B. Positive pressure, C. Negative pressure, D. Sclerotherapy
C: Negative pressure
Answer: C: Negative pressure 
Explanation: Ans. (C) Negative pressure(Ref: Bailey & Loves Short Practice of Surgery 27th Ed; Page No-30)Negative Pressure dressing (VAC dressing) which exertsa pressure of -125 mm Hg and hastens wound healing in chronic wounds.It can be used for:#Venous ulcer without slough#Burns wounds without eschar#Bedsores without slough#Diabetic foot ulcer without osteomyelitis