Step 1: Break down the phrase given.
"No injury is done to a person who consents" is about voluntary acceptance of a risk removing liability.
Step 2: Match this to the correct maxim.
Volenti Non Fit Injuria literally means "to a willing person, no harm is done," which is exactly this defence in tort law.
Step 3: Eliminate the other maxims.
Res Ipsa Loquitur deals with facts speaking for themselves, Res Judicata bars re-litigating a decided matter, and Quid Pro Quo is about an exchange of value - none fit the consent idea.
\[ \boxed{\text{Volenti Non Fit Injuria}} \]