Why did the Dred Scott v. Sandford decision anger Northerners?

It made slavery legal in the territories.

It sought to continue the series of compromises on slavery.

It allowed for expansion of slavery into the North.

It created popular sovereignty as the rule for all territories.

The decision angered Northerners because it made slavery legal in the territories, thereby allowing for the expansion of slavery into areas where it had previously been prohibited. This went against the growing sentiment in the North against the institution of slavery.