Yolanda is correct since the boulders have a circular shape, the best shape to model the surface area of a sphere.
A sphere is a three dimensional object that has all the set of all points equidistant from a single point in space. An example of a sphere is a ball. The boulder in this question has a spherical shape.
Surface area of a sphere = 4πr²
To learn more about the surface area of a sphere, please check: https://brainly.com/question/27267844
#SPJ4