Lenin, stalin, and trotsky were all members of the
aristocracy
bourgeoisie
intelligentsia
proletariat

Option C, intelligentsia

Explanation:

Intelligentsia is a group of people that are part of the elite segment of the society and are involved in shaping the artistic, political, cultural forms of the society. This group includes artesian, politician, writers, thinkers, teachers, journalist etc.  

Lenin was a proactive Russian revolutionary politician, Stalin was a politician serving the position of General secretary of  the communist party of soviet union and Tortsky was both a theorist and politician  of the soviet union.

sound moves fastest in solids because the molecules are tightly packed and it allows sound to vibrate

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