If $$a_{1}, a_{2}, a_{3}$$ and $$a_{4}$$ is the decreasing order of the elements in the set
$$\left\{ \frac{2}{7}, \frac{7}{15}, \frac{5}{8}, \frac{9}{20}\right\}$$ then $$a_{2} + a_{3}$$ =

A

$$\frac{2}{7}$$

B

$$\frac{17}{56}$$

C

$$\frac{19}{56}$$

D

$$\frac{11}{12}$$