Explanation:
"The very first period to get a pseudonym had been the period of the 1920s: for so many, "Roaring 20s" included economic development and easy going lifestyle. The period started with a roar and finished with a collapse.
Following the Battle of Stalingrad, A. German troops continued their blitzkrieg eastward. The battle was very bloody and lasted for 5 months in 1943, two years before the end of the WWII.
The correct answer would be 15 states