Marine organisms adapted to the coldest temperatures and the highest salinity levels would inhabit which zone?

The correct answer is: Abyssopelagic or Hadalpelagic zones, because these zones are deepest marine zones.

There are 5 main marine zones (and a few subzones):

1. Epipelagic zone (200 m) - the sunlight zone where is s most of the life in the ocean.

2. Mesopelagic (1000 m) - the twilight zone many of the organisms who live in this zone have special adaptations

3. Bathypelagic (1-4000 m) - the midnight zone

4. Abyssopelagic (4-6000 m)

5. Hadalpelagic zones (6-11000 m).