What term describes a crowd expressing support or opposition to authority or a political cause?

The term that accurately describes a crowd expressing support or opposition to authority or a political cause is "demonstration." This term specifically refers to a public gathering of individuals who come together to express their views regarding political or social issues. Demonstrations can take various forms, including marches, rallies, or sit-ins, and are typically organized to raise awareness or advocate for a specific cause.

While other terms may relate to similar situations, "demonstration" clearly encompasses both the intent and nature of the event, which is to publicly showcase support or opposition to certain beliefs or policies. It implies a non-violent approach focusing on raising awareness and influencing public opinion, making it the most appropriate choice in this context.