Which of the following statements about convection is true?

Convection is a heat transfer process that occurs within fluids, which include both liquids and gases. The statement that convection transfers thermal energy within fluids is accurate because it describes how warmer, less dense regions of a fluid rise while cooler, denser areas sink, resulting in a circulation pattern that facilitates the transfer of heat. This process is crucial for distributing thermal energy throughout the fluid, whether it's in boiling water or atmospheric circulation.

The other statements misrepresent fundamental aspects of convection. Convection does not occur only in gases; it is also present in liquids, as seen in cases like heated water or oil. It does not occur in vacuum conditions, as the absence of fluid eliminates the mechanism for convection to function. Lastly, convection is indeed influenced by temperature differences, as these differences drive the movement of fluid and the resulting heat transfer. Thus, the true statement about convection is that it effectively transfers thermal energy within fluids.