Solve the below equation.
$$\frac{1 + 2}{\left\{ 1 + \frac{2}{(1 + \frac{1}{3})}\right\}} = ?$$

A

$$\frac{9}{4}$$

B

$$\frac{6}{5}$$

C

$$\frac{21}{4}$$

D

$$\frac{21}{5}$$