A dart board is a regular octagon divided into regions as shown. Suppose that a dart thrown at the board is equally likely to land anywhere on the board. What is the probability that the dart lands within the center square?

**Answer Choices**

A. \dfrac{\sqrt{2}-1}{2}

B. \dfrac{1}{4}

C. \dfrac{2-\sqrt{2}}{2}

D. \dfrac{\sqrt{2}}{4}

E. 2-\sqrt{2}