$$\frac{4+3\sqrt{3}}{7+3\sqrt{3}} = a + \sqrt{b}$$, then $$a - \sqrt{b} =$$

A

$$ 8 + \sqrt{75}$$

B

$$ -8 + \sqrt{75}$$

C

$$ -8 - \sqrt{75}$$

D

$$ 8 - \sqrt{75}$$