The answer is letter b. honor. Brutus decided to support Cassius and the
conspirators despite his relationship with Caesar. He felt that Caesar was getting too powerful
and wanted to bring back the old days of the Republic. Sadly, he would later die along with the
other conspirators.
The best way to do so is by stating your claim, and use evidence to support it. If there is no evidence to support your claim, it is simply just an opinion and people will have no reason to think you are right.