What is one of the four variants of the Mercator projection?

The Web Mercator variant is a specific application of the traditional Mercator projection that was developed primarily for use in web mapping applications. It maintains the characteristic properties of the Mercator projection, including the preservation of shape and angle, making it particularly useful for navigation and displaying spatial data on a flat surface. Its widespread adoption by online mapping services, like Google Maps, has made it a standard in GIS applications that require interactive map displays.

Web Mercator is distinguished by its use of spherical coordinates rather than ellipsoidal ones, simplifying calculations for online map rendering but introducing some distortions, especially at higher latitudes. This makes it ideal for certain types of web applications where speed and performance are prioritized over absolute accuracy.

The other options represent different map projections that do not derive from the Mercator projection. The Hammer projection and the Sinusoidal projection, for example, are composite projections that aim to reduce area distortion and provide different visual representation methods compared to the Mercator family. Goode's Homolosine projection is an equal-area projection that is designed to maintain the proportional size of landmasses but distorts shapes and angles more than Mercator.