\textbf{170-} In the figure of a U-tube, the pressure difference at point A and the air pressure is how many kilopascals?
$$\left(g = 10\,\frac{\text{N}}{\text{kg}},\ \rho_{\text{water}} = 1\,\frac{\text{g}}{\text{cm}^3},\ \rho_{\text{mercury}} = 13.6\,\frac{\text{g}}{\text{cm}^3}\right)$$
\textit{[Figure: A U-tube with water on one side and mercury on the other; point A is marked on the water side; the water column is $40$ cm and mercury column is $60$ cm]}
\begin{itemize}
\item[(1)] $13.6$
\item[(2)] $136$
\item[(3)] $130$
\item[(4)] $60$
\end{itemize}