The best correction of the clause fragment is to C. delete the word "although."
Without that word, you get a proper single independent sentence, and not a fragment.
A friend is someone difficult to find. A friend is someone you can always count on when times are tough.
Answer:
Sorry. no answer to your question.
C. In the afternoon, we walked together to the rehearsal hall
-"In" being the preposition.
Hope this helps!
