Oxygen from the atmosphere reaches the mammalian blood stream through one of the paths indicated below. Indicate the correct api A= mouth b = trachea c = bronchioles d= nostrits e-broncos f= alveoli

• A.a-> b- e - f -d
• B.b-d-f-e-c
• C.d- b-e-o-f
• D.f-e-c-d-c