Think: How would you get anywhere without one of these things. I would say the answer is C, choosing a topic. You can complete any of these steps without choosing what you will be working on.
Answer:
There are many reasons we need to protect wilderness: Wilderness protects watersheds that provide clean drinking water to surrounding communities. Wilderness filters and cleans the air we breathe. Many animals we love call wilderness their home.
In A: it should be "I was" not "I were".
In B: it should be "lately you appear" not "you appears"
in C: this is correct! the subject is in agreement with the verb, and this is the correct answer.
in D: it should be "you are"