The assembly line would be my first choice.
Answer:
The battle of Stalingrad prevented Germany from successfully gaining control of Moscow.
Explanation:
Germany's failure to capture Stalingrad ultimately led to Germany's failure to capture Moscow and defeat the Soviet Union. Capturing Stalingrad would've given Germany access to the USSR's oil supply, giving the Germans the upper hand against fighting the Russians. They weren't able to successfully capture and had to back off from the offensive.
<em>Good luck, i hope this helps :)</em>
The factors that made it difficult for Eastern Europe to improve its water quality were outdated sewer systems, raw water quality, worn-out water utilities and unskilled employees. So we can say that four options given in the question fits the bill perfectly. These basic infrastructural reasons were responsible for being a hurdle towards improving the water quality. <span />
<span>The interaction between imperial china and central Asian nomads change after 1100 CE. This was the blooming of China's civilization and its venture into the political world and inevitably expanding its territories to Central Asia. In return, China became the center point for politics and economy on that era.</span>