The correct option is option D ("Evidence of the Nazi 'final solution'").
In places such as Auschwitz and Buchenwald, the worst of all atrocities were being uncovered, as that's where the concentration camps were located.
The Nazis often referred to their plan to annihilate all jewish population as the "Final Solution". In the concentration camps, an innumerable amount of innocent people were tortured and executed resulting in one of the biggest genocides in history.
Hope this helps!
