Biology · Kingdom Animalia

Heterotherms are those animals who are capable of varying degrees of endothermic heat production but generally do not regulate their body temperature within a narrow range.

Heterotherms are those animals who are capable of varying degrees of endothermic heat production but generally do not regulate their body temperature within a narrow range. 

b) Endotherms: Endothermic animals, often referred to as warm-blooded, have the ability to maintain a relatively constant internal body temperature regardless of the external environment. They generate heat internally through metabolic processes to keep their body temperature within a narrow range. Hummingbirds fall into this category as they can maintain a consistent body temperature. 

c) Ectotherms: Ectothermic animals, commonly known as cold-blooded, rely on external sources of heat to regulate their body temperature. They do not produce enough metabolic heat to maintain a stable internal temperature and therefore their body temperature tends to match that of their surroundings. Hummingbirds are not ectotherms. 

d) None of these: This option implies that hummingbirds do not belong to any of the mentioned categories (heterotherms, endotherms, or ectotherms), which is not accurate based on our understanding of their thermoregulation.