At Some Point We Will Have Used Up the Oil

At some point we will have used up the oil on Earth. Do we need to worry about that? Why or why not?

A) No. The U.S. oil consumption is already going down, so we're learning to conserve and use other sources for energy. We'll have enough oil.
B) No. Science will certainly come up with a better energy source than oil any year now.
C) There's really no way to know, but better safe than sorry.
D) Yes, because even though U.S. oil consumption is down, as other countries develop like we already have, their consumption goes up. We're going to need some other energy source.
E) Yes, because the United States needs an ever increasing supply of oil, not just for energy but for many of our products. We may have to plan to guard what we have and fight for what's in other countries.