Which one of the following is a possibility for most of us in regards to breathing, by making a conscious effort

Options

A. One can consicously breathe in and breathe out by moving the diaphragm alone , without moving the ribs at all
B. The lungs can be made fully empty by forecally breating out all air from them
C. One can breathe out air totally without oxygen
D. One can breathe out air through eustachina tubes by closing both nose and mouth.

Answer

A