\textbf{154.} Which set is a minimal vertex cover for the graph below?
\medskip
\textit{[Figure: Graph with vertices $a, b, c, d, e, f, g$ and edges connecting them]}
\medskip
(1) $\{a, c, e, g\}$
(2) $\{a, d, e, g\}$
(3) $\{a, b, d, e\}$
(4) $\{a, d, e, f\}$
\medskip