Assume that a given question has several answers.
So in the answer part there are 3 button "Active", "Oldest" and "Vote"
When we clique on "oldest", we lead to a unique answer.
Is this unique answer the first answer to the question?
I doubt that the answer to this meta question is affirmative since it does not work for example on this question
On the other hand the situation is different for the following question with several answers
So what does "oldest" signify?