The correct answer is increasing density, increasing pressure
A dolphin dives into the ocean. As it descends it experiences increase in density and decrease in temperature . As the dolphin moves down the ocean the salinity of the water increases, this also contributes in increasing the density of water. The pressure increases down the ocean level due to increase in the hydrostatic pressure. As the dolphin will go down it will feel increase in pressure. Dolphin will feel the water pushing it .