The answer is option D) The point where the fence post enters the ground.
Explanation:
Given,
The fence above the ground= 6 feet
The fence below the ground= 4 feet
Total height of the fence= (6 feet +4 feet)= 10 feet
option A) The middle of the fence is somewhere between 0 feet and 10 feet. It may be any value (example: 2 feet or 5 feet or anything between 0 to 10).
option B) The top of the fence is the topmost point of the fence which is 6 feet from inside the ground and 10 feet from above the ground.
option C) The bottom of the fence is 4 feet from the ground and 10 feet from the top of the fence.
option D) The point where the fence post enters the ground represents the exact point along the ground. The point is a (small dot mark) which is 0 feet.