I honestly think that any answer is going to be less truthful than those proffering it think. People who say they'd do it, no problem, what ever it takes to survive? Sorry, I refuse to believe that such is absolute truth of you or anyone. We've seen too many instances in this country of people that have gone out of their way in terrible circumstances that are a risk to them physically or even certain death. People ran back into the World Trade Center and the Pentagon when attacked. Men volunteered to re-enter nuclear reactors and expose themselves to lethal radiation after the Tsunami destruction in Japan. I don't think glib internet posts capture the full story of human beings...
On the other hand... I feel the same way about anyone thinking that they KNOW for sure that they will always act with the noblest intentions, despite harm to themselves. Until you are in a situation it's easy to say, "Oh, of course I will do the right thing as I've been taught since a child." That's presumptuous. We don't know how we would react, how fear for life and limb can make our inner coward our outer coward.
I think that if you are the type of man that goes on about how you feel the current culture is "feminizing" men (Dear Zod...) and that our leaders are weaklings ext. and your "honest" response to this question is, "Sure, no problem, I'd belt that chick and her 3 year old", well... You may have some issues to work out about stuff.
I would like to THINK that I would do what I believe is right under the circumstances but I for sure don't know that. I do know that I and others have seen that people have laid their lives down for other human beings.