Why did the confederates burn richmond as president davis and his cabinet fled?
to stop northern soldiers from capturing the confederate president
to make sure the union army could not use confederate resources
to wage war against any union soldiers who were already in the city
to rebel against the ineffective tactics of the confederate government

To make sure the Union Army could not use Confederate resources.

Explanation:

On Evacuation Sunday (April 2, 1865), President Davis, his Cabinet, and the Confederate guardians left Richmond and escaped south on the last clear railroad, the Richmond and Danville. The retreating troops were following orders to set fire to bridges, the armory, and sheds with supplies as they fled, to make them useless for the Federalists. Union troops put out the flames.

answer; taking up arms to defend the nation;