Final answer:
Elie Wiesel at first disbelieved the horrifying sight of crematoriums burning bodies. These represented the atrocities of the Holocaust and the brutal extermination of millions at camps like Auschwitz, where soldiers like Lt. Col. Felix L. Sparks were shocked at scenes of mass murder upon their arrival.
Step-by-step explanation:
The horrifying sight that Elie Wiesel at first disbelieved was b) Crematoriums burning bodies. Upon arrival at the concentration camps during the Holocaust, the liberating soldiers, including those like Lieutenant Colonel Felix L. Sparks, encountered scenes of unimaginable horror. They witnessed extermination camps with facilities designed for mass murder, including gas chambers and crematoriums. Many of these soldiers were unable to fathom the atrocities committed, despite being hardened by the realities of combat.
These camps were a physical manifestation of the Nazis' meticulous and systematic genocide that resulted in the deaths of millions of Jews and others deemed undesirable by the regime. A major mechanism of this genocide were the gas chambers, which were misleadingly presented as 'showers' to the prisoners. Afterward, the 'work Jews' were assigned the ghastly task of cremating the remains, until eventually, they too, were exterminated.
Camp liberators were profoundly affected by the sights of starved, beaten, and brutalized inmates, often left where they had fallen, with the liberation troops being the first witnesses to the aftermath of these crimes against humanity. This initial disbelief at the scope of Nazi atrocities underscores the sheer scale and brutality of what occurred during the Holocaust.