The correct answer is A) they wanted to punish them for helping the south.
Union forces destroyed Native American property because they wanted to punish them for helping the south.
Although Native American Indians split sides during the CIvil war for different reasons, a considerable number of Native Americans supported the Confederacy against the Union. Historians consider that almost 8,000 natives that lived in the Indan territory (modern-day Oklahoma) supported the army of the Southern states. Most of the Native Indians belonged to the so-called "Five Civilized Tribes," the Choctaw, Cherokee, the Seminole, the Creek, and the Chickasaw.