Answer:
The language he uses is German.
Step-by-step explanation:
Doktor Pannwitz was an officer in the German army. He was responsible for testing whether Primo Levi had sufficient knowledge to work in the chemistry laboratory in the concentration field.
Primo Levi portrays that they spoke German and although Levi was able to understand the language very well and speak satisfactorily Pannwitz looked at him with an air of superiority, as if Levi were a filthy and unworthy creature, Pannwitz does not see Levi as a human being .