Isn't a hypothesis making a theory? Based on that I guess the answer would be A. Making a theory, because you making the hypothesis is not part of testing it.
I think the correct answer would be the first option. The process that would explain this phenomenon is convection. It is a mode of heat transfer which is a result of bulk movement of a substance due to the difference in density which is a result of the temperature of these substances. This transfer of heat is applicable to fluids. When the temperature of a fluid increases, the fluid expand thus decreasing its density. However, for a fluid which has a cooler temperature, it would contract resulting to a much higher density. Therefore, the warm fluid would rise up while the cooler fluid would sink below the warm fluid.
As a wave enters a different medium the characteristic that does NOT change is the frequency.
Probably because the earth is stationary rotating on its axis whereas the baseball is the one doing all of the movement after being thrown