<prompt> In below capnograph the red pa represent:-Alveolar ventilation of expirationInspirationExpirationDead space ventilation  <response>: First phase A-B represents the initial stage of expiration. Gas occupying anatomic deed space, devoid of Co2 represent this phase. Second phase B-C- represent a sharp upstroke when Co2 containing alveolar gas presents at sampling site. Third phase C-D - represents alveolar phase Fouh phase D-E - inspiration begins and fresh gas is entrained and touches baseline. Phase C-D may take an upward slope. Point D is the highest Co2 value and is called the end-tidal Co2 ET Co2. ET Co2 is the best reflection of the alveolar Co2 PA Co2. Normal value of ET Co2 - 35-45 mm of Hg. 