Let G be a graph with n vertices and m edges. What is the tightest upper bound on the running time of Depth First Search on G, when G is represented as an adjacency matrix?

In a depth-first traversal of a graph G with n vertices,k edges are marked as tree edges. The number of connected components in G is

Consider the following graph among the following sequences
I. a b e g h f
II. a b f e h g
III. a b f h g e
IV. a f g h b e
What are depth first traversals of the above graph?