Answer:
it's a type of frame thing for an image. i will try to describe it: the edges of the image fade instead of it being rectilinear.
example of vignette frame
notice how the image fades into the edges
C. To clearly state the main idea of the paragraph
There was an old lady who swallowed a cow.
I don’t know how she swallowed a cow!
She swallowed the cow to catch the goat.
She swallowed the goat to catch the dog.
She swallowed the dog to catch the cat.
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider
That wriggled and jiggled and wiggled inside her.
She swallowed the spider to catch the fly.
But I dunno why she swallowed that fly.
Perhaps she’ll die