Where could convection currents form? check all that apply. in a sand dune in a freshwater lakein the atmospherein outer spacein earth’s mantle?

Convection currents form in atmosphere and freshwater lake. Convection currents occur when there is difference in temperature in both substances (eg. fluids). When there is a difference in temperature, the hot substance rises and the colder one sinks. The flow then will be form a hotter to the colder region. 

The correct answer would be lost aquila

Answer (d) may increase or decrease porosity through dissolution or deposition;