What are the lines that run parallel to the equator called?

The correct choice is the term "Parallels of Latitude." These lines are specifically defined as the circles that run horizontally around the Earth, parallel to the equator. They are used to denote the latitude of a location, which indicates how far north or south a point is from the equator. Each line of latitude is measured in degrees, starting from the equator at 0° and extending to the poles at 90° north and south.

In contrast, meridians and lines of longitude refer to vertical lines that run from pole to pole, representing the Earth's division of time and location along the east-west axis. Great circles, on the other hand, are not specifically parallel to the equator; they are the largest circles that can be drawn on a sphere and can intersect the equator but are defined by their equal division of a sphere, playing a significant role in navigation and timekeeping. Understanding latitude and how these lines function is crucial for navigation, mapping, and geographical orientation.