Which one of the statements below describes the direction of thermal energy transfer in an isolated system? In an isolated system, for energy transfer to take place the entire system must remain at a constant temperature. In an isolated system, energy always transfers from a warmer region to a cooler region In an isolated system, energy always transfers from cooler region to a warmer region In an isolated system, no transfer of energy between regions of the system can take place. In an isolated system, energy cannot be transferred from a hotter region to a colder region.