Read this excerpt from "Hope, Despair, and Memory" by Elie Wiesel and answer the question. The survivors wanted to communicate everything to the living: the victim’s solitude and sorrow, the tears of mothers driven to madness, the prayers of the doomed beneath a fiery sky. They needed to tell of the child who, in hiding with his mother, asked softly, very softly, "Can I cry now?" They needed to tell of the sick beggar who, in a sealed cattle-car, began to sing as an offering to his companions. And of the little girl who, hugging her grandmother, whispered: "Don’t be afraid, don’t be sorry to die … I’m not."

What historical context does Wiesel convey using the allusion of a fiery sky?

He compares the sky to hell.
the fires from air raids during World War II
the cremation of Jews in the concentration camps
the outbreak of forest fires from bombs in World War II