What is surface area?
A any of the individual surfaces of a solid object
B a pattern of two-dimensional shapes that can be folded to make a model of a solid figure
C a solid figure with a base that is a polygon and sides that are triangles that meet at
D the top the total area of the surface of a solid figure

D

Explanation:

The surface area of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc length of one-dimensional curves, or of the surface area for polyhedra, for which the surface area is the sum of the areas of its faces. Smooth surfaces, such as a sphere, are assigned surface area using their representation as parametric surfaces.

the outside part or uppermost layer of something (often used when describing its texture, form, or extent)

they gained popular support by speaking out against communists

in the united states. ( d.)