Which category of terrain is classified as having significant obstacles but still passable?

The classification of terrain with significant obstacles that are still passable is referred to as "Restricted" terrain. This type of terrain typically includes features such as thick forests, urban areas, or hilly regions, which may slow movement and require careful navigation. While these obstacles present challenges, they do not completely hinder movement, allowing for tactical maneuvering and logistics.

The term "Unrestricted" describes terrain that poses no significant impediments, allowing for free movement and full operational capability. On the other hand, "Severely Restricted" refers to terrain that imposes so many challenges that movement is extremely limited, often necessitating specialized equipment or techniques. "Completely Obstructed" terrain denotes areas where movement is impossible due to barriers such as walls, cliffs, or no-pass zones, making it unusable for tactical purposes. Thus, "Restricted" accurately characterizes terrain that has significant obstacles yet remains passable, leading to its selection as the correct answer.