You Notice That in Your Aquarium, Previously Full of Undoubtedly

You notice that in your aquarium, previously full of undoubtedly male fish, one is laying eggs.Upon a bit of research, you find out that the species of fish you purchased is a sequential hermaphrodite.Which of the following is true?

A) One of the male fish underwent protandry and became a female.
B) One of the male fish fertilized its own eggs.
C) Since the fish are hermaphrodites, one of the male fish laid eggs and another will likely fertilize them.
D) The fish have parthenogenesis, therefore their eggs do not have to be fertilized to be viable.