Choose the correct option to fill in the blank in the flow chart:
\begin{center
\begin{tikzpicture}[
every node/.style={draw, rectangle, minimum width=2.5cm, minimum height=1cm, align=center},
level 1/.style={sibling distance=6cm},
level 2/.style={sibling distance=5.5cm},
level distance=1.5cm
]
\node {Minerals}
child {node {Metallic}}
child {node {Non-metallic}
child {node {Fuel mineral
Example -- Coal}}
child {node {Other non-metallic minerals
Example \_\_\_\_}}
};
\end{tikzpicture}
\end{center}}