Consider the following graph:
Which one of the following cannot be the sequence of edges added, in that order, to a minimum spanning tree using Kruskal’s algorithm?
- $(a-b),(d-f),(b-f),(d-c),(d-e)$
- $(a-b),(d-f),(d-c),(b-f),(d-e)$
- $(d-f),(a-b),(d-c),(b-f),(d-e)$
- $(d-f),(a-b),(b-f),(d-e),(d-c)$