What was the purposes of "killing centers"?

The Nazis established killing centers for efficient mass murder. Killing centers were almost exclusively “death factories.” They are also referred to as “extermination camps” or “death camps.” Nazi concentration camps, by contrast, served primarily as detention and labor centers. At the killing centers, Nazi officials employed assembly-line methods to murder Jews and other victims. German SS (Schutzstaffel; Protection Squadrons) and police murdered nearly 2,700,000 Jews in the killing centers by asphyxiation with poisonous gas or by shooting.

“the iliad” (gr: “iliás”) is an epic poem by the ancient greek poet homer, which recounts some of the significant events of the final weeks of the trojan war and the greek siege of the city of troy (which was also known as ilion, ilios or ilium in ancient times).

may i have the answer choices?