What is defined as the governing body of a nation, state, or community?

The term that best describes the governing body of a nation, state, or community is "Government." A government is a formal organization that holds the authority to create and enforce laws, manage public policy, and administer public services at various levels, whether it be local, state, or national. It encompasses the institutions and structures that work to uphold and manage the governance of a community or society, ensuring order and implementing regulations for the welfare of its citizens.

The other choices do not encapsulate the entirety of the concept of governance in the same way. For instance, "Municipal" specifically refers to the local or city level of government and does not represent the broader spectrum of governance at all levels. "Authority" can refer to a body or entity that has the power to enforce laws or make decisions, but it does not explicitly denote the overarching structure of governance. Similarly, "Agency" usually refers to a specific organization or administrative body that performs particular functions but lacks the comprehensive view of governance that the term "Government" provides. Thus, the selection of "Government" reflects the most accurate representation of the governing body within a societal context.