If $$\frac{{4 + 3\sqrt 3 }}{{\sqrt {7 + 4\sqrt 3 } }} = A + \sqrt B {\text{,}}$$then B - A is = ?

• A. 13
• B. ${\text{2}}\sqrt {13} $$
• C. 3
• D. ${\text{3}}\sqrt 3- \sqrt 7 $$