I would shoot World Hunger, and here's why:
War is an essential part of humanity. It has been raging for our entire existence, but it does slack at some points. Hunger never does. There is always hunger somewhere. Hell, I'm hungry right now, but that can't even compare to the terrible, starving, complete lack of food some people have to deal with on a daily basis.
I would not shoot myself becasue 100 years is a pitiful amount of time for there to be no war or hunger. It implies that no matter what happens during that time, war and hunger will be back afterwards, so that there is really very little use of 100 years of peace.
I would not shoot war because of my earlier statements, though I have other reasons as well. First of all, I may be slightly sociopathic, as the chaos of war excites me. It gets me-for lack of a better term-high, though I have never done drugs. I feel elated and happy, like I'm flying and full of wonder. But anyway, I digress.
The World Wars of the past have never lasted very long, even though they had catastrophic impacts on the world's population. I can assume that while there would be more war, it would only last in bursts, with probable areas of peace in between.
Now, this question begs another: is it assumed that the option that was not shot (of hunger and war) will be solved in the future, or is it simply doomed to perpetuate for the rest of human existence?