D, because your brain is what makes almost all of your organs work.
If there were a fire, explosion, or bomb threats in schools, for example, are required to evacuate but if it's a sniper or shooter then they do a lockdown. Because if the shooter is on the outside and they decide to evacuate then they could get shoot so most schools and places do lockdowns.
So the answer would be a sniper. I hope this helps!
I'd say it's to set up a clear goal.
