Please help! Help would be amazing!!! 2 questions!

  1. Deepwater currents are driven by which of the following?
Atemperature only
Bsalinity only
Ctemperature and salinity
Dtemperature and pressure

  1. Upwelling is the upward replacement of ________, nutrient-poor, surface water by ________, nutrient-rich, deep water.
Acooler, warmer
Bwarmer, cooler
Csaltier, warmer
Dcooler, saltier