Many hospital employees backgrounds include medical degrees.

the correct answer is the first option "the bolkshevik revolution". the passage makes reference to many of important events that occured in the revolution, such as the assemblies, in this case the animals are gathered in an assembly after a protest, the murder of fellow partners, the speeches given by the leader of the revolution, among other aspects. the last choice is possible, but in this passage in particular it is not emphasized the fight between the characters, that is the two pigs, that represent lenin and stallin.