How did national identities form in the 1800’s?

National identity is not an inborn trait and it is essentially socially created! It is something you pick up from values,traits and beliefs. Especially after spending a considerable amount of your time with people of certain nationalities. This is perhaps how it was formed! People back then had a spoken,written language, Different values/morales, Traits and unique culture! There perhaps wanted a way to make their culture and beliefs distinct so they made national identities!

the answer would be:

b. race

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