The revision that uses subordination to revise the example is C: "Although it took me a while to get used to the new software, now I like it". Subordinate clauses begin with a subordinate conjuction or a relative pronoun and contains a subject and a verb. However, they are dependent because they do not express a complete thought and therefore cannot stand on their own.
*Although it took me a while to get used to the new software
As you can see, the sentence does not express a complete thought. That is why it is grammatically incorrect.
