Which of the following marine animals migrates to freshwater for spawning?

Which of the following statements are correct for $Cyclostomata$?
$I$ - They have a sucking and circular mouth without jaws.
$II$ - Their body is devoid of scales and paired fins.
$III$ - Their cranium and vertebral column are cartilaginous.
$IV$ - They have a closed type of circulatory system.
$V$ - $Cyclostomes$ live in freshwater, but migrate to the ocean for spawning.
$VI$ - They show direct development.

The jawless vertebrate is

The larva of $Petromyzon$ is known as

Which jawless fish lays eggs in freshwater,and after metamorphosis,its $Ammocoetes$ larvae return to the ocean?

Which of the following is present as an excretory organ in hagfish?