Which term refers to bold resistance to authority or an opposing force?

The term that best describes bold resistance to authority or an opposing force is "defiance." This word conveys a strong sense of challenge and assertiveness against established rules or adversaries. When someone exhibits defiance, they are often standing firm in their beliefs or actions, choosing to confront rather than comply with the demands or expectations set by those in power.

In contrast, the other options do not relate to the concept of resisting authority. "Decimate" typically refers to the act of destroying a significant portion of something, often used in contexts such as reducing a population or systematically dismantling a structure. "Dainty" describes something delicate or fine, which does not imply any form of resistance. "Deluge" refers to a severe flood or an overwhelming amount of something, which again has no connection to the idea of boldly opposing authority. Therefore, defiance is the appropriate term to describe such resistance.