Animals of which phylum have hooks and suckers and are endoparasites on other animals?

Which of the following animals belongs to the phylum $Platyhelminthes$?

Which phylum of animals lacks organ systems?

Which of the following is true for $Taenia$?

The animal group that is acoelomate is:

"Triploblastic, unsegmented, acoelomate exhibiting bilateral symmetry and reproducing both asexually and sexually, with some parasitic forms". The above description is the characteristic of phylum: