Final answer:
The incorrect statement about the Buna is that it produced an endless supply of rubber; in fact, its production faced many difficulties and was not endless.
Step-by-step explanation:
The statement that is not true of the Buna is 'c. The Buna produced an endless supply of rubber.' The Buna, also known as Auschwitz III or Monowitz, was indeed a massive factory complex that operated like a city, as indicated in option 'b.' It was constructed and operated by the German Nazi regime and its name came from the type of synthetic rubber, Buna rubber, that it was intended to produce. Primo Levi, a Holocaust survivor, worked there, as mentioned in option 'a.' Additionally, the workforce was composed of prisoners from various concentration camps, in line with option 'd.'