Solution
= Solution
\b[True.] A <tree> has exactly one path between any two <vertices>. For $e\notin T$, that path between the endpoints of $e$, together with $e$, is a <fundamental cycle>. Every cycle in $T\cup\{e\}$ must contain $e$, since $T$ itself is <acyclic>; deleting $e$ from such a cycle leaves that same unique path. Therefore the cycle is unique. Minimality of the spanning tree's weight is not needed for this assertion.