There are a lot of things you can do without, but also a lot of things that you cannot live without, including (some of the more obvious examples) - brain - heart (artificial or natural) - lungs - cardiovascular system (i.e. Not just the heart, but also blood vessels) - stomach - intestines (which absorb nutrients from food consumed, water from liquid consumed, etc.) etc.
I'd say the brain. There are life support systems that work to keep the lungs taking in oxygen and expelling CO2, a machine can keep the heart pumping and circulating blood. When it comes down to it, if the brain stops working from injury or disease, there is no way to keep it working and alive.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.