The circuit consists of three branches connected between points \( A \) and \( B \), each having a \( 1 \, \Omega \) resistor in series with voltage sources of \( 3 \, \mathrm{V} \), \( 2 \, \mathrm{V} \), and \( 1 \, \mathrm{V} \), respectively. The current in each branch can be calculated using Ohm's Law:
\[
I = \frac{\text{Voltage}}{\text{Resistance}}.
\]
\begin{itemize}
\item For the top branch: \( I_1 = \frac{3}{1} = 3 \, \mathrm{A} \),
\item For the middle branch: \( I_2 = \frac{2}{1} = 2 \, \mathrm{A} \),
\item For the bottom branch: \( I_3 = \frac{1}{1} = 1 \, \mathrm{A} \).
\end{itemize}
Since all resistances are equal, the potential difference between \( A \) and \( B \) is determined by the branch with the highest voltage source. Hence,
\[
V_{AB} = 3 \, \mathrm{V}.
\]