How does composite area help determine the surface area of a three dimensional figure?

Definition
A composite 3D figure is a three dimensional figure made up of basic three dimensional figures such as cubes, prisms, pyramids, cylinders, cones, etc.

To find the surface area of a composite 3D figure, add the areas of each geometric figure making up the composite 3D figure.

To find the volume of a composite 3D figure, draw any necessary planes to view the figure as basic three dimensional figures, then:
add basic figure volumes belonging to the composite shape
subtract basic figure volumes NOT belonging to the composite figure

Iknow one of the answers is a and maybe b but not 100% sure about b