Spend a lot of time on your essays. My impression of Wellesley’s admissions process is that they put a lot of emphasis on “fit”, as someone stated earlier in the thread. Make sure you request an interview before the deadline passes. Talk about your extracurricular activities and how they make you a good fit for Wellesley. The D isn’t a deal-breaker; people have gotten in with one low grade. What matters is how you explain it. Generally, it’s a good idea to take responsibility and describe how you learned and grew.