Which of the following is the best example of deep breathing?

There are multiple ways of "deep breathing" and no one way is better than another. It is simply a matter of which works better for you. I'd suggest trying a few different ways before settling on one. A lot of the time, people don't breathe deep enough when trying to perform this exercise. Make sure you are focused only on your breathe, and really work at it. Over time, your breaths will get deeper and deeper.