What is the BEST description of a change proposal?

Any RFC submitted to change management describes the general change request process, not the specific nature of a change proposal.

An authorized change submitted to release and deployment describes a later stage in the change lifecycle after approval, not the proposal stage.

An RFC that must be implemented as soon as possible describes an emergency change, not a change proposal.

A change proposal is used to justify a change that involves significant cost, risk, or resource requirements before a full request for change is submitted. It provides decision-makers with enough information to evaluate feasibility and business justification. This is distinct from a standard RFC in that it precedes the detailed planning phase and is focused on high-level justification.