Question 19Eight points are spaced at intervals of one unit around a $2\times2$ square, as shown. Two of the $8$ points are chosen at random. What is the probability that the points are one unit apart? $ \ \dfrac{1}{4} $$ \ \dfrac{2}{7} $$ \ \dfrac{4}{11} $$ \ \dfrac{1}{2} $$ \ \dfrac{4}{7} $
