BFS Question

A BFS was performed on an unknown graph, producing the following visitation order:

a-c-d-b-f-g-e-h

There are four candidate graphs:

I)

II)

III)

IV) 

Assuming that neighbors are always visited in ascending order, which of the graphs are valid candidates for the original graph?

a) I and II

b) I and III

b) II and IV

d) III and IV

e) None of the above

Original idea by: Pedro Zaffalon da Silva