Answer: Most likely the industrial revolution.
Explanation: The use of machines in production became more and more prevalent, eventually many factories were built in cities which caused pollution therefore making the air gross.
Answer:
Hitler achieved power in March 1933, subsequent the Reichstag raised the Enabling Act of 1933 in that month, proffering extended authorization. President Paul von Hindenburg had previously elected Hitler as Chancellor on 30 January 1933 after a group of parliamentary elections and connected with backroom intrigues.
Explanation: