Simplify:  $$\sqrt{51 +\sqrt{134+5\sqrt{42+ \sqrt{16}+\sqrt{9}}}}$$​​

Correct option is D

Solution: 

​$$=\sqrt{51 +\sqrt{134+5\sqrt{42+ \sqrt{16}+\sqrt{9}}}} \\ \ = \sqrt{51 +\sqrt{134+5\sqrt{42+ 4+ 3}}} \\ \ = \sqrt{51 +\sqrt{134+ 35}} \\ \ = \sqrt{51 +\sqrt{169}} \\ \ \ = \sqrt{51 + 13} \\ = \sqrt{64} \\ =\bf 8$$​​