another philosophy question

I knew there was one more question that I wanted to put down. Here it is:

Say you and a friend are hiking when suddenly your friend falls and breaks his leg. You don't have any cell phone reception and oyur friend can't move. You tell him that you will be right back and you run back to the car. When you get there you still don't have reception and the car won't start. You notice a car close to yours and happen to see that the keys are in the car also. Would you take the car? What if the owner of the car comes back before you can get the car back? Is it considered stealing?

Philosophy

Here are some questions/scenarios that I had to think about in my philosophy class.

1) Can God create a rock so heavy that he can't lift it?

2) You are shipwrecked on an island so you decide to go look around. You come upon a group of natives who are about to sacrifice a nine year old girl to their gods. The natives have not seen you yet. What do you do?

3) You are a hospital administrator and you have five nobel peace prize winning scientists in your hospital all needing a different organ. These scientists are all discovering a cure for some life threatening illness. Suddenly, a homeless guy walks in with a broken arm and you find out that he is a perfect match for all five scientists. He has no family or friends no one to miss him, he used to be a banker but embezzled so much money and was discovered and fired. What would you do?

Well, those are actually the only things I wanted to pose to you all. Please, tell me what you think especially about the third one.