A frog sitting at the point (1,2) begins a sequence of jumps, where each jump is parallel to one of the coordinate axes and has length 1 , and the direction of each jump (up, down, right, or left) is chosen independently at random. The sequence ends when the frog reaches a side of the square with vertices (0,0),(0,4),(4,4), and (4,0). What is the probability that the sequence of jumps ends on a vertical side of the square?

**Answer Choices**

A. \dfrac{1}{2}

B. \dfrac{5}{8}

C. \dfrac{2}{3}

D. \dfrac{3}{4}

E. \dfrac{7}{8}