I don't think there will be any decision making in the process but the action will be pure instinct and I have a gut feeling that most people will go for the child. As our genes would have it, I think we will go towards saving the future generation that has only lived a short life span, than saving someone who has lived a fair share. I think, even when one experiences parenthood, the attention, and focus shifts from the partner to the child. And from an evolution standpoint, men and women may have different reactions to the said situation. One gets more caring about the child, as i think our brain starts signalling to us that the young one needs protection till it is growing. This in my opinion is quite contrary to the notion that a person should save the adult in a life threatening situation, as they are more likely to find companionship with them, than the child. However, based on evolutionary instincts, i think most people will save the child.