The value of $$60 \div \left[50 + 7- \left\{14 + \left(24 of 2 \div 3\right) - 12 \div 4 \times 2 + 18 \div 4 \times 2\right\}\right]$$ is:

A

1

B

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

C

2

D

$$\frac{5}{4}$$