Nationalism. As Manifest Destiny was geared towards more of the individual people's growth (i.e go-getters) compared to Nationalism; the growth and advancement of the nation's people's as a whole.
Explanation:
Slaves are those people who are bound by the authority of someone and are meant to serve that authority
The Eastern Front was much more terrible, for example, every German officer who would violate discipline in any way, one of the sentences was going to the Eastern Front. In addition, much more human casualties were on the Eastern Front, the way of fighting differed due to the nature of the relief. While the Western Front was mainly taking place in the territory of France and Belgium, although not just there with the trench warfare, the Eastern Front line spanned over a thousand miles, more precisely from the Baltic Sea in the north, to the Black Sea in the south, and extended to parts of the Central Europe, so that the trench warfare was unimaginable.
The answer is: D.
