Final answer:
The meridian used by a surveyor is defined as an average line within the rectangular survey system area in which the land being surveyed is located.
Step-by-step explanation:
The meridian used by a surveyor is defined as an average line with the directional value assigned by the observer within the rectangular survey system area in which the land being surveyed is located (option d).
This means that the meridian is chosen based on the location of the land being surveyed and is not necessarily in the same state or closest to the land. It must be within the rectangular survey system area that the land belongs to.
For example, if the land being surveyed is located in a certain township and range within the rectangular survey system, the meridian chosen would be within that specific area.Surveyors follow a grid system that divides land using a rectangular pattern, helping to eliminate confusion and disputes over property boundaries that previously arose from the metes and bounds system.