The sum of n terms of the series \(\frac{1}{{\sqrt 3 + \sqrt 7 }} + \frac{1}{{\sqrt 7 + \sqrt {11} }} + \frac{1}{{\sqrt {11} + \sqrt {15} }} + \cdot \cdot \cdot \) is
1
\(\frac{{\sqrt {3 + 4n} + \sqrt 3 }}{n}\)
2
\(\frac{n}{{\sqrt {3 + 4n} + \sqrt 3 }}\)
3
\(\sqrt {3 + 4n} + \sqrt 3 \)
4
\(\frac{1}{{\sqrt {3 + 4n} + \sqrt 3 }}\)