When should a hunter obtain permission to hunt on private land?

It is important for a hunter to obtain permission to hunt on private land before they start hunting. Option A is incorrect because the hunter should not assume that they have permission to hunt just because they have already begun hunting. Option B is incorrect because some private land may not be posted, but that does not mean the hunter has permission to hunt. Option D is incorrect because it is always necessary to obtain permission before hunting, regardless of whether or not people are around. It is important for hunters to respect private property and obtain proper permission before accessing it. This ensures the safety of both the hunter and the landowner.