If $f:R\rightarrow S$ defined by $\:f(x)=\sin x-\sqrt3\; \cos x+1\;$ is onto function then $S$ = ?

Question

$\begin{array}{1 1} [0,1] \\ A\subset B \\B\subset A \\ A=B \\ A\:and\:B\; are\; disjoint\; sets. \end{array}$