An animation is made up of individual images called
a. thumbnails
b. hot spots
c. icons
d. frames

D. Frames

Explanation:

An animation is made up of individual images called FRAMES.

The term refers to old film ribbons where each image was presented in a frame, on the long film ribbon that would be moving in front of a light to project the movie images.

A. Thumbnails: they're a small version of an image.

B. Hot spots are areas that can be clicked to link somewhere else for example.

C. Icons are small images, can be animated or not.

we need a link or picture : )