What Is the Definition of a Standard

What is the definition of a standard?

A) A predetermined baseline condition or level of excellence that constitutes a model to be followed and practiced
B) Diagnosis-based, step-by-step interventions for nurses to follow in an effort to promote evidence-based, high-quality care
C) Process of measuring products, practices, and services against those of best-performing organizations
D) Identify not only what and how an event happens but why it happens, with the end goal being to ensure that a preventable negative outcome does not recur