Carcass sir, which line states the theory put forward by the passage ?

"Studies of tribes with more territory often show that reconnaissance and sepulchering had separate domains"

The 30 or 40 mounds discovered up to this time in this region of the Takawgamis have, so far as examined, a uniform structure. Where stone could be obtained, there is found below the surface of the ground a triple layer of flat limestone blocks, placed over the remains interred. In one mound, at the point where the Rainy Lake enters the Rainy River, there is a mound situated in which there was found on excavation, a structure of logs some ten feet square, and from six to eight feet high. In all the others yet opened, the structure has been simply of earth of various kinds heaped together. It is possible that the mound containing the log structure may have been for sacrifice, for the logs are found to have been charred. One purpose of all the mounds of the Takawgamis was evidently burial, and in them all, charcoal lumps, calcined bones, and other evidences of fire are found. Would this conclusion antagonize the theory that the mounds were used for observation? Perhaps with a limited amount of land, the Takawgamis, by necessity, built structures with a dual purpose.

Until now the passage tells us about facts , relevant, about some sort of excavations

Studies of tribes with more territory often show that reconnaissance and sepulchering had separate domains.

This last sentence tells us that that the phenomenon is more common than we thing, studying more territories. Therefore, this is the correct sentence to use and the right option