The correct option is A Ichthyornis
Ichthyornis was a genus of toothed seabirds from the Late Cretaceous of north America.
Ichthyophis is a genus is caecilians found in southeast Asia, southern Philippines and the western Indo-Australian Archipelago.
Ichthyosaurus is the genus of dinosaurs or reptiles from the late Triassic and early Jurassic of Europe.
Ichthyostega is an early tetrapod genus that lived at the end of the upper Devonian period.
Thus, the correct answer is (A), Ichthyornis.