In a cool environment, an ectotherm is more likely to survive an extended period of food deprivation than would an equally sized endotherm because the ectotherm . a) maintains a higher basal metabolic rate b) expends more energy per kilogram of body mass than does the endotherm c) invests little energy in temperature regulation d) has greater insulation on its body surface

c) Invests little energy in temperature regulation

Explanation:

Ectothermic animals are the organisms which are dependent on the external sources of heat in order to regulate their internal body temperature. In these organisms the mechanism for the regulation of heat through internal physiological process is absent. Due to such feature they don't need to spend energy to maintain the body heat in cool environment and thus they can operate at a very economical metabolic rate. And thus they became enable to survive for longer even in the condition of food deprivation.

Explanation:

1. Ectotherm: Ectotherm are cold-blooded animall whose regulation of body temperature depends on external sources, such as sunlight and many other environmental factors.

2. They do not maintain their body temperature by self, so their body temperature changes  externally.

3. They are also known as cold blooded animals.

3.They invests little energy in temperature regulation.

4. Example of  ectotherms:  include the fishes, amphibians, reptiles, and invertebrates.