Answer: I think your claim is great as long as you have evidence that you can support it with and feel comfortable commenting on that evidence to link the causes and their importance.
Step-by-step explanation:
you stated the causes of the civil war very efficiently but the prompt asks you to evaluate their importance so in your writing I think that you need to make sure to acknowledge why those causes were important and how they led specifically to the civil war. You started this by saying they were all sources of disunity I would just go a step further and explain why that makes them important and why they led to the civil war.
Does that make sense? Let me know if you have any questions. I hope I helped a little. Ap classes are hard but just keep going you got this!