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

Options

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

Answer

D