Which of the following statements about Earth's shape is true?

The statement that Earth is an oblate spheroid is true because it accurately describes the planet's shape. An oblate spheroid is a body that is slightly flattened at the poles and bulging at the equator, which corresponds closely to the actual shape of Earth. This shape arises from the rotation of the planet, causing the equatorial region to extend outward due to centrifugal force.

In contrast, describing Earth as a perfect sphere does not take into account the equatorial bulge caused by its rotation. The notion of a cubical shape is inconsistent with extensive geodetic measurements and understanding of planetary formation. Additionally, suggesting that Earth's shape changes frequently misrepresents the stability of its geometric form, as any changes in shape happen over geological time scales due to processes like tectonic activity, but not in a frequent or significant manner. Thus, the oblate spheroid classification is the most accurate representation of Earth's shape in the context of geospatial sciences.