What was the system by which branded cattle were allowed to graze freely on unfenced property? a. land grant c. vigilante

In the Western United States and Canada, open range is rangeland where cattle roam freely regardless of land ownership. Where there are "open range" laws, those wanting to keep animals off their property must erect a fence to keep animals out; this applies to public roads as well. Land in open range that is designated as part of a "herd district" reverses liabilities, requiring an animal's owner to fence it in or otherwise keep it on the person's own property.

Militarism is the answer.