WHO KNOWS THIS SONG Tu amor es devoto como anillo en santa unión
Como voto probado, como antiguos pactos son
Tu amor permanece en la tempestad
Por encima de todo, tan lleno de piedad

Not me, because I only know English.

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.