Correct option: A.$\tan \theta = \frac{{\sqrt 3 + \sqrt 2 }}{{1 - \sqrt 2 }}$
a
For particle $C,$
According to law of conservation of linear momentum, verticle component,
$2\,mv'\,\sin \,\theta = mv\sin {60^ \circ } + mv\,\sin {45^ \circ }$
$2mv'\sin \theta = \frac{{mv}}{{\sqrt 2 }} + \frac{{mv\sqrt 3 }}{2}\,\,\,\,\,\,\,\,\,\,\,\,\,...\left( i \right)$
Horizonatal component,
$2\,mv'\,\sin \,\theta = mv\sin {60^ \circ } - mv\,\sin {45^ \circ }$
$2mv'\cos \theta = \frac{{mv}}{2} + \frac{{mv}}{{\sqrt 2 }}\,\,\,\,\,\,...\left( {ii} \right)$
Dividing $e{q^n}$ $(i)$ by $e{q^n}$ $(ii),$
$\tan \theta = \frac{{\frac{1}{{\sqrt 2 }} + \frac{{\sqrt 3 }}{2}}}{{\frac{1}{2} - \frac{1}{{\sqrt 2 }}}} = \frac{{\sqrt 2 + \sqrt 3 }}{{1 - \sqrt 2 }}$
