Looking at the three directed graphs:

For each of the graphs, answer the following:

If a topological sort can be performed on this graph, show the results of the sort, and briefly explain how this result was obtained.

If a topological sort does not exist for this graph, explain why.
 

A B G Directed Graph 1 C H A D B E Directed Graph 2 C A F B G E Directed Graph 3 H