I would say the answer is D.
That is because in that number line 2 is included which would not make the club "official". It needs 5 or more members. If the dot was at 5 then the dot would have been shaded. Since its less, which isnt "official", the dot should not be shaded. But the line is pointed in the correct direction since it needs more than 2 memebers. So it increases to the right.
Hope this helps ;P