Here is the item again:
All my friends wanted to spend Friday afternoon at the beach. Except Michael,
the worrier, who was concerned about shark bites, jellyfish stings, and
skin cancer.
You chose to alter the fragment so that it now contains a main clause, like this:
All my friends wanted to spend Friday afternoon at the
beach. Michael,
however, was
concerned about shark bites, jellyfish stings, and skin cancer.
Well done! You deserve that cyber sundae!