Take a look at the item again:
With the huge number of confusing rules colliding in her
head, (A)
Cindy took the quiz on fragments
(B) and
hoped, (C)
that she would remember enough of the material to pass.
You wanted to do this:
With the huge number of confusing rules colliding in her head, Cindy took
the quiz on fragments, and hoped, that she
would remember enough of the material to pass.
Adding a comma after fragments will make an error. When you have only two items—in this case, took and hoped—the and alone is enough. No comma is necessary with the and.
You might want to review the rules.
Go back to the sentence to try again.