One of the central conflicts in the play centers around the future leadership of rome.
1 antony desires to march to sardis to face brutis and cassius
2 brutus accuses cassius of being corrupt
3 brutus gives his speech at caesar's funeral
4 brutus and cassius are defeated at philippi

Brutus accuses Cassius of being corrupt. Option 2 is correct.

In the story, Brutus refered openly to how Cassius is untrustworthy due to the fact that he received a lot of bribe from merchants and people from other kingdom. Brutus was seeking to damage public's perception regarding Cassius and make them doubt Cassius' credibility.

Brutus is the most complex character in Julius Caesar and is also the play's tragic hero.

Cassius is described as a manipulative man who uses Brutus's good nature and character in an attempt to destroy the life of Julius Caesar.

given the fact that the question is about the detail that best support the idea that oppressive leaders use   propaganda to achieve thir goals,   the first option does not refer to any kind of propaganda, since it only tells about that the milk and the windfall apple should be reserved for the pigs. in the second option, that is, "snowball and napoleon sent out flights of pigeons whose instructions were to mingle with the animals on the neighbouring farms, tell them the story of the rebellion, and teach them the tune of "beasts of england". it can be identified that the oppressors make use of the propaganda, which is represented by the pigeons, and the information they have to tell other animals about what was happening in the farm in order to get their objectives. for that reason, the right answer is the second option, taking into account that the third option do not refer to propaganda since it only talks about that they did not want jones back. and, finally, the last option refers to the result of the given news, but it does not mean about the propaganda they used to achieve their goals.

this is a good question! i'll do some research and come back when i have the answer!