Question

The most important gas for humans:
(a) Nitrogen
(b) Oxygen
(c) Argon
(d) Helium

Answer 1

many gases are useful to the human...

but the most important is oxygen,

it serves for respiration, burning, and many other purposes ....!

Answer 2

Answer:

b.oxygen .

Explanation:

because to break the food into its simple form that is glucose(C6H12O6) which is required to all cells of our body, then further it is been converted into ATP (energy) by mitochondria