Take a look at the passage again:
To save money on a haircut that he badly needed. Raja let Tina, his roommate
and an aspiring stylist, trim his shaggy head.
Honestly, a blender or a weed whacker could have done a better job!
You chose the third part, Honestly, a blender or a weed whacker could have done a better job! This part has a main clause: whacker is the subject; could have done is the verb. A fragment will not have a main clause.
Go back to the passage to try again.