Answer:
D
Step-by-step explanation:
The reason that Antarctica is unclaimed is due to the Antarctic treaty signed by 12 developed nation in 1956 (and since then 38 nations) which states that no nation can claim the region. This treaty was aimed at protecting the continent’s ecozone (from military operations and mineral exploitation, etc) that is essential or the planet. Due to the harsh environment on the continent, it is also inhabitable and is more or less unoccupied.