OpenStudy (anonymous):

The surface area of a sphere is found using the formula 2003-05-05-00-00_files/i0140000.jpg, where r is the radius. If the surface area of a sphere is 642003-05-05-00-00_files/i0140001.jpg square feet, what is the radius, in feet? A. –4 B. 16 C. 4 D. –16