The nose is an organ that acts as an airway for oxygen to enter the body. the nose also contains hairs that trap small foreign objects and stop them from entering the body. which two systems does the nose play a role in?

a.
respiratory and immune
b.
digestive and excretory
c.
immune and digestive
d.
excretory and respiratory

A. The oxygen means it's a respiratory, and the hairs act to ensure no foreign contaminants make you sick.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

it is the most commonly accepted one