Ethnicity is like your culture. Language, race, and religion all play into your background and culture. However, politics are something that govern the country you live in -- they're not necessarily connected to your background. Therefore, politics would be the correct answer.
I would have to say the answer is Patriotism
The 1920's saw a period of rapid industrialisation, which made the decade to be correctly called the Roaring twenties. However, it is only the industrialists who benefited from the boom, with the majority of the working population conditions remaining poor. This was a fragile situation that led to the great depression as few money was circulating in the larger population. This has led to some conspiracy theorists attributing the blame of the great depression to the industrialists and bankers.
Religious intolerance. ...
Intolerance of those who were different. ...
Intolerance of the poor
Hunger and poverty
Various deadly diseases were spread into Europe
