What is the term used to describe the surface of equal gravity if Earth were covered by oceans?

The term "Geoid" describes the surface that represents equal gravity across the Earth, assuming it were covered entirely by oceans. It reflects the mean sea level and accounts for variations in gravitational pull due to the Earth's uneven distribution of mass. The geoid is a theoretical shape of the Earth that illustrates how gravitational forces vary across the planet, influenced by factors like terrain, water bodies, and the Earth's rotation.

In contrast, the "Ellipsoid" refers to a mathematically defined surface that approximates the shape of the Earth but does not account for gravity variations in the same way as the geoid. The "Spherical Model" is a simplified representation of the Earth as a perfect sphere, neglecting the real complexities of its gravitational field. "Oceanography Surface" is not a standard term used in geography or geodesy, making it less relevant. Thus, the correct answer highlights the importance of understanding Earth's gravity variations and their implications in GIS applications.