JEE Math Practice Question

If $$f(x) = \left\{ {\begin{matrix} {{{\sin (a + 2)x + \sin x} \over x};} & {x < 0} \\ {b\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,;} & {x = 0} \\ {{{{{\left( {x + 3{x^2}} \right)}^{{1 \over 3}}} - {x^{ {1 \over 3}}}} \over {{x^{{4 \over 3}}}}};} & {x > 0} \\ \end{matrix} } \right.$$ is continuous at x = 0, then a + 2b is equal to :

1. A.0
2. B.-1
3. C.-2
4. D.1