I believe the best answer to be the first option as well: A) Although we have paid for our trip, we still need to find chaperones for the event.
Explanation:
Since our purpose is to transition smoothly between the first and the second paragraphs, we should choose a sentence that links the topics presented in both.
The first paragraph is ended by stating that funds were raised to cover the expenses of the trip. The second one makes it clear that more help is necessary and that, so far, they have only one chaperone. Thus, the best way to connect the two ideas presented above would be by using option A) Although we have paid for our trip, we still need to find chaperones for the event.
