Let $S$ be the set of all real roots of the equation, $3^{x}\left(3^{x} - 1\right) + 2 = \left|3^{x} - 1\right| + \left|3^{x} - 2\right|$, then\\
(1) contains exactly two elements.\\
(2) is a singleton.\\
(3) is an empty set.\\
(4) contains at least four elements.