From a regular octagon, a triangle is formed by connecting three randomly chosen vertices of the octagon. What is the probability that at least one of the sides of the triangle is also a side of the octagon? (2018 AMC 8 Problems, Question \#23) 
选项为:A:$\frac{2}{7}$  B:$\frac{5}{42}$  C:$\frac{11}{14}$  D:$\frac{5}{7}$  E:$\frac{6}{7}$  请回答其中一个选项.