C. Highlighting the important elements using her own note-taking key
Explanation:
Sarah would benefit from highlighting the important elements using her own note-taking key. When you're studying from notes, it's important that you create them in a way you understand them. That's why people often have trouble learning from someone else's notes. Everyone learns in their own way. That's why Sarah should use her own note-taking key.
I believe the answers you wrote are already correct, except for #3 because the verb, had. I think both might be correct in this situation. Keep up the great work!
