The value of $$1\frac{19}{21}-[1\frac{10}{21}+\frac{1}{2} \ of \ \frac{1}{3}\div\frac{7}{12}-(\frac{2}{7} \ of \ \frac{1}{5})]$$ is:

A

$$\frac{1}{5}$$

B

$$\frac{3}{5}$$

C

$$\frac{2}{5}$$

D

$$\frac{1}{10}$$