\textbf{199-} Which of the following statements about semiconductors is correct?
\begin{enumerate}
\item[(1)] Transistors exist only in P-type semiconductors.
\item[(2)] At very low temperatures, semiconductors act like insulators.
\item[(3)] At very low temperatures, semiconductors act like conductors.
\item[(4)] In semiconductors, as temperature increases, electrical resistivity also increases.
\end{enumerate}