The answer is sex cells or gametes
Air enters into the body through nose and proceeds to pharynx or windpipe afterwards it proceeds down and reaches to larynx the voice box and continue to proceed to trachea which is surrounded by rings so that by air pressure it cannot be collapse from there a divides into two side left and right bronchus then it conducted towards bronchioles which is the pathway to alveoli at last it reaches to its Final Destination (not that movie....hahah) which is alveoli where the exchange of gases takes place
The answer is A: least explosive
