Which of the following characterizes a capricious decision by an administrative agency?

A capricious decision by an administrative agency is characterized by a lack of established agency policy. This means that the agency makes decisions that appear arbitrary or unreasonable because they are not guided by consistent principles or established procedures. In administrative law, agencies are expected to follow their own rules and policies to ensure that their decisions are predictable and fair. When an agency does not adhere to its established standards or shifts course without justification, it risks being labeled as acting capriciously.

The other options, while important in the context of administrative decision-making, do not directly relate to the idea of capriciousness. For instance, consistency with existing law and reliance on credible evidence are indicative of sound decision-making practices, while a rational basis for policy changes suggests a thoughtful and reasoned approach, neither of which align with the notion of capriciousness where predictability and rationale are lacking.