Which one of the following statements are correct?

(i) Respiration in total involved 5 steps.

(ii) The movement of air into and out lungs is carried out by creating pressure gradient between lungs and the atmosphere.

(iii) Inspiration occur if the pressure within the lungs is more than the atmospheric pressure.

(iv) Expiration takes place when intra-pulmonary pressure is lower than atmospheric pressure.

(v) Inspiration is initiated by the contraction of diaphragm which increases the volume of thoracic chamber in the antero-posterior axix.

(vi) During inspiration, contraction of external inter-costal muscle lifts the ribs and the sternum causing an increase in the volume of thoracic chamber in dorsoventral axis.

(vii) Humans have the ability to increase the strength of inspiration and expiration with the help of additional muscle in the abdomen.

(viii) On an average, a healthy human breathe 12-16 times/minute.

(ix) The volume of air involved in breathing movements can be estimated by using a spirometer which does not help in clinical assessment of pulmonary functions.

(x) Approximately 500 ml of air is inspired or expired during forceful respiration and a healthy man can inspire or expire approximately 6000-8000 ml of air per minute.

Choose the correct option given below: