The correct answer is - it had a strategic location along the Volga River.
Stalingrad was a city of great interest because it had an excellent strategic position. It was located alongside the Volga River, which is extremely important for inland trade because its waters a navigable, and it also connects very important parts of Russia. Another even bigger reason for the attack on Stalingrad by the Germans, was that it was very close to the big oil reserves, and the Germans needed every single barrel that they can get.
