Take a look at the passage again:
To stay awake for a long evening of chemistry homework.
Beth made a huge pot of coffee. Unfortunately,
her heart beat so fast and her legs jiggled so violently that the poor girl
couldn't concentrate.
You chose the second part, Beth made a huge pot of coffee. This part has a main clause: Beth is the subject; made is the verb. A fragment will not have a main clause.
Go back to the passage to try again.