Which of the following best characterizes the domain of amphibians?

The correct characterization of the domain of amphibians includes being cold-blooded and laying eggs because amphibians, which encompass frogs, toads, salamanders, and newts, exhibit these defining biological traits. They are ectothermic (cold-blooded), meaning their body temperature is regulated by the surrounding environment. This characteristic influences their habitat choices and behavior.

Additionally, amphibians have a distinct reproductive strategy, as they typically lay eggs in water or moist environments to ensure that the eggs remain moist and are less vulnerable to desiccation. This reflects their evolutionary connection to aquatic environments during their larval stage, where they usually develop into tadpoles before metamorphosing into their adult forms, which may be either terrestrial or semi-aquatic.

Considering the other options, being primarily aquatic or primarily terrestrial does not fully capture the dual life cycle of amphibians, which includes both aquatic (larval) and terrestrial (adult) phases. The idea that they are adapted only to land is inaccurate, as many species rely on aquatic habitats for breeding and the survival of their young to complete their life cycle. Thus, the combination of these traits in option C accurately reflects the unique and adaptable nature of amphibians in their ecological niche.