B) Buna
Inside his story "Night", by Elie Wiesel (Eliezers), they first arrived at Buna, where they were divided into groups, one for women, and the other for men (the last time Elie saw his mother and sisters), and Elie and his dad was led into Buna, a work concentration camp.
Note: The general area was near Auschwitz/Birkenau*
hope this helps