Which one of the following is a true fish as per the biological system of classification?

Cuttlefish or cuttles are marine animals of the order Sepiida. They belong to the class Cephalopoda, which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone. Despite their name, cuttlefish are not fish but molluscs.

Jellyfish are soft bodied, free-swimming aquatic animals with a gelatinous umbrella-shaped bell and trailing tentacles.