I think answer should be only III i.e. ‘1’ invocations of Floyd-Warshall algorithm ⇒ Ο(V3).
Reason for saying this –
As we know for complete graph number of edges , E = V(V-1)/2 nearly equal to V^2 , so for complete graph
I.‘V’ invocations of Dijkstra algorithm ⇒ Ο(VE logV) becomes O(V^3logV)
II. ‘V’ invocations of Bellman-Ford algorithm ⇒ Ο(V2 E) becomes O(V^4)
III. ‘1’ invocations of Floyd-Warshall algorithm ⇒ Ο(V3) remains O(V^3) only.
Hence considering best cases for all types of graph one must prefer option III