Which of the following statements about map projections and geographic coordinate systems is not true?
a. Because the Earth is essentially spherical, high-accuracy and high-precision large-scale mapping can be done globally using a single global datum.
b. Different reference ellipsoids are frequently used for large-scale mapping of different areas of the Earth given the nature of the geoid.
c. A theoretical three-dimensional reference ellipsoid is called a datum.
d. Many map projections use theoretical developable surfaces to transform three-dimensional features into two-dimensional representations.
