What is a characteristic of "non-propositions"?

The characteristic that non-propositions do not make a claim that can be evaluated is accurate because non-propositions lack the qualities necessary to be classified as statements that assert something that can be true or false. Non-propositions may include questions, commands, or exclamations, none of which express a declarative statement that can be assessed for truth value. This fundamental aspect highlights their nature as expressions that do not advance an argument or a claim.

In contrast, the other options focus on aspects that do not apply to non-propositions. While opinions might seem subjective, they can still be structured as propositions capable of being evaluated based on individual beliefs or preferences. Claims about a statement being true or false pertain directly to propositions, as they inherently seek to establish validity or accuracy. Lastly, expressing certainty is characteristic of propositions that assert definite statements, whereas non-propositions typically do not convey certitude or judgment about reality.