What were the causes of the american civil war?

The cause of the American Civil War was that the North was no longer willing to tolerate slavery as being part of the fabric of US society and that the political power brokers in Washington were planning to abolish slavery throughout the Union. Therefore for many people slavery is the key issue to explain the causes of the American Civil War.

The answer is challenging and taxing because arduous means when something is hard and tiring and the excerpt provides clear detail why that's the answer