The correct answer is C.
In this story, the reality is that these young men are all greatly injured. It is unlikely they will ever be able to do normal activities -- like playing football -- again. The doctor's words, however, reflect the opposite of reality, and the reader is aware of it.
Therefore, it is ironic when the doctor tells the injured soldier that he "will play football again like a champion." It is clear to the reader that this young man will never play football again. The doctor's words are ironic.