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

Options

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

Answer

C