Please only do Part $($b$).$ Need Help for part $($b$)$ ONLY $!$

Question $3$

$($b$)$ Let $G$ be a simple connected graph and $v$ be a vertex of $G.$ We apply Dijkstra's algorithm

to find shortest paths from $v$ to all the other vertices in the graph. The edges of these

shortest paths will form a spanning tree $T$ rooted at $v.$ Prove or disprove that diam$(T)$

$2$diam$(G).$