Answer to Question 1
The ocean consists of three horizontal layers. The mixing zone is the surface layer, which is warmed by the Sun and mixed via the action of wind. The mixing zone represents approximately 2 of the oceanic mass. In this layer, variations in water temperature and salinity vary. Below the mixing zone is the thermocline transition zone. This zone, which is more than 1 km thick, has a gradient of temperature that decreases with depth. There is also friction in this layer, so the effects of surface currents are negligible. The colder waters also inhibit convective movements. The thermocline zone accounts for about 18 of oceanic mass. From depths of about 1-1.5 k to the ocean floor is the deep cold zone, which accounts for 80 of the oceanic mass. Here the waters are near 0C (32F), but do not freeze due to the dissolved salts.
Answer to Question 2
A