Valid orderings for topological sort I am reading Algorithms by Dasgupta et al and the graph section provides an example graph and mentions that there are 4 orderings with one of them being B, A, D, C, E, F.

Are the other 3?

B, A, D, C, F, E
B, D, A, C, E, F
B, D, A, C, F, E
You can answer your own question by checking whether, for each edge $(u,v)$ of the graph, $u$ appears before $v$ in each of the three candidate topological orders that you listed.