Final answer:
Political philosophers often focus on whether a revolution is justified when examining a revolution.
Step-by-step explanation:
The question is asking which aspect political philosophers often focus on when examining a revolution. The options given are whether a revolution is justified, legal, violent, or successful. The correct answer is A. Justified. Political philosophers often consider whether a revolution is morally justifiable, meaning whether it is based on a valid reason or cause. They analyze the underlying moral issues that lead to a revolution and assess whether the use of violence or other means is justified to bring about change.