Which was the most likely reason the bodies of victims at Auschwitz were cremated?

The Nazis and SS wanted to burn the bodies of not only Jews but other Sub-Humans because, both Hitler and Himmler realized with the increasing number of deported prisoners from camps to camps, they need to dispose the bodies as quickly but also as efficient as possible and crematories can burn from 12- 300 people per crematory varying on size of the dead prisoners.