The answer is C) The forest Ulrich von Gradwitz is patrolling is a tract of land that both Gradwitz and George Znaeym lay claim of ownership.
The text explains that “…Georg Znaeym, the inheritor of the quarrel and the tireless game-snatcher and raider of the disputed border-forest.” It is clear that there was a dispute overa strerch of land and both Ulrich and Gradich claimed their ownership.
The idea of patrolling is present in “…his wind-scourged winter night Ulrich had banded together his foresters to watch the dark forest..” Here we are told that Ulrich needs to protect what he considers his property from Gradwitz.