<prompt> A 25 year old male is undergoing incision and drainage of abscess under general anaesthesia with Spontaneous respiration. The most efficient anaesthetic circuit isMaplelson AMapleson BMapleson CMapleson D  <response>: Mapelson breathing systems are classified as Mapelson A, B, C, D, E, F Mapelson A also known as Magill;s circuit. Ranking of Mapelson;s systems based on superiority as follows : Spontaneous ventilation : AD,F,EC,B Controlled ventilation : D, F, EB,CA Mapelson A is more efficient in spontaneous ventilation Mapelson D is more efficient in Controlled ventilation 