The true statement is:
"Ectotherms cannot insulate (stop heat loss from) their bodies and can only control their body temperature by changing location."
Ectotherms, such as reptiles and amphibians, rely on external environmental conditions to regulate their body temperature and usually do so by moving to different locations. They lack the physiological mechanisms to insulate body heat like endotherms (e.g., mammals and birds) do.