Quiz: MST Edge in ALL

Edges in MST: Determine if an edge appears in ALL possible MSTs. Edge $(u, v, w)$ appears in all MSTs if:

1. A.Both endpoints have degree $1$
2. B.Removing it disconnects the graph, or all alternative paths have strictly heavier bottleneck
3. C.It's the minimum weight edge in the graph
4. D.It's part of the shortest path tree