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

Normally the inspired air constitutes about 20.84% of oxygen whereas the expired air constitutes about 15.7% of oxygen. And even if one holds his or her breath, it is not possible to breathe out air totally without oxygen.
The eustachian tube is a canal that connects the middle ear to the nasopharynx. It controls the pressure within the middle ear, making it equal to the air pressure outside the body. No one can breathe out air through eustachian tubes by closing both the nose and the mouth.
Yes, one can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all.
The lungs cannot be made fully empty by forcefully breathing out all air from them. Residual volume is always present in the lungs, even after the maximum forceful expiration effort. It is about 1500 ml of the air.
So, the correct answer is 'One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all.'