The situation that best exemplifies the theme of power in The Tragedy of Julius Caesar is Mark Antony and Octavius’ argument regarding Lepidus’ suitability for the Second Triumvirate. So the answer to your question would be letter D.
You need to be more specific when asking questions like this. First of all, you should copy the second paragraph of whatever you are reading. After doing that, you will be able to get a suitable answer for your question.
D. Students acting the parts of prisoners and guards
Not something they’re able to get for one another!