Final answer:
The Nazis considered Slavs to be racially inferior and sought to eliminate them as part of their genocidal policies, driven by pseudo-scientific racial theories and expansionist aims in Eastern Europe.
Step-by-step explanation:
The Nazis killed the Slavs primarily because they were considered inferior by the Nazi racial ideology and, as a result, they were targeted in the Nazi’s genocidal policies. This ideology professed that the Slavs, as an ethnic group predominantly from Eastern Europe, were subhuman and a threat to the so-called purity of the Aryan race. The Nazi regime, fueled by extreme hatred, was influenced by pseudo-scientific racial theories and nationalism, which coalesced into a worldview in which Slavs and other groups were to be either subjugated or eliminated. Furthermore, as the Nazi armies invaded territories in Eastern Europe, the occupation policies involved the brutal treatment of Slavic populations, including the exploitation for labour and the mass murder as part of the broader aims of Lebensraum, which sought to expand German territory into the East and forcibly remove populations deemed undesirable.