The city's bid to host the international conference was considered a long shot given its limited experience hosting large events. ______,…

The second sentence describes a successful outcome despite the disadvantage named in the first sentence, limited experience, and nevertheless signals exactly that kind of contrast: success achieved in spite of an obstacle. Similarly would suggest agreement between the two sentences, but "long shot" and "secured the bid" are in tension, not alignment. For example would frame the second sentence as an illustration of the first's claim, not a contrast with it. Consequently would incorrectly suggest the successful bid was a direct result of being a long shot, reversing the actual relationship.