What term defines the stake whose top is used as a reference point to establish elevation and distances?

The term "Hub and blue top" refers to a specific type of survey stake utilized in construction and excavation projects to establish critical reference points for elevation and distances. The "hub" is typically a stake driven into the ground, and the "blue top" is a colored cap placed on top of the hub, which is used to ensure visibility and quick identification. This combination allows surveyors and construction professionals to accurately determine elevations and distances necessary for grading and alignment, serving as a consistent point of reference throughout the project.

The other options, while related to surveying, do not encapsulate the precise usage and identification characteristic of "Hub and blue top." For instance, "Marker" and "Reference point" are more general terms that could apply to any point of reference without the specific context of elevation and distance associated with construction projects. "Survey stake," while applicable, does not specifically denote the marker's purpose in establishing elevation when defined with a blue top. Therefore, the specificity and clarity of "Hub and blue top" make it the most accurate choice for this context.