we will use formula
[tex] \theta=\frac{180(n-2)}{n} [/tex]
Here ,
theta is angle
n is number of sides
we are given octagon
so, n=8
we can plug n=8 and then we can find angle
[tex] \theta=\frac{180(8-2)}{8} [/tex]
[tex] \theta=\frac{180*6}{8} [/tex]
so, we get
[tex] \theta=135 [/tex]
so, option-B....................Answer