Answer:
E) sustainable competitive advantage
Step-by-step explanation:
Competitive advantages refer to the things that Harley Davidson does better than other motorcycle companies, e.g. cool bikes. While sustainable advantages refers to competitive advantages that other motorcycle companies cannot imitate at least in the short run, e.g. that feeling of belonging to a special club.
Harley Davidson bikes have a "je ne sais quoi" mystique that other companies don't have. I'm sure that Honda, Ducatti, KTM, BMW and maybe others actually produce better bikes, but there is no Honda bike club or BMW bike club, or at least none that people want to join.