Hello. You did not enter answer options, which makes it impossible to create an answer exactly.
However, we can say that Hitler's objectives in invading Stalingrad was to have access to industrial production in the region, in addition to having access to the source of minerals and oil that Caucaso, in a city near Stalingrad, presented.
In this way, he would not only be able to use these products to enrich German reserves and have more strength to continue advancing his domination plan.