A square, whose side is 2 m, has its corners cut away so as to form an octagon with all sides equal. Then the length of each side of the octagon, in metres, is

A

$$ \frac{\sqrt 2}{\sqrt 2 +1} $$

B

$$\frac{2}{\sqrt 2 + 1} $$

C

$$\frac{2}{\sqrt 2 - 1}$$

D

$$\frac{\sqrt 2}{\sqrt 2-1} $$