Threads are not closed in the board, there is no such mechanism. However, we mark a post as solution to help the future readers of this question. If there is an answer that you believe helps with the question, even a bit when there is not an exact solution (even saying "it is not possible" could be an answer btw), or if you post your own answer, then that would be great to see it marked it as the solution.
I would normally select post #2 as the best response to this question, however, I won't switch it, but leave the decision to you.
However, if you believe there is no post related to the solution then please do not mark any post.