Final answer:
Gigantotherm is a synonym of c) inertial homeotherm, which describes large animals that maintain stable internal temperatures due to their size.
Step-by-step explanation:
Gigantotherm is a synonym of option c: inertial homeotherm.
An inertial homeotherm is an organism that maintains a relatively stable internal body temperature due to its large body mass, which allows it to resist rapid changes in temperature. This term differs from ectotherms, which are organisms that rely primarily on environmental heat sources to maintain their body temperature.
An animal that maintains a constant body temperature in the face of environmental changes is called an endotherm. Unlike ectotherms, endotherms generate internal heat that keeps their cellular processes operating optimally, allowing them to maintain a level of activity that is not possible for ectotherms, especially in cold environments.