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

During its life cycle,$Fasciola$ $hepatica$ $(Liver$ $Fluke)$ infects its intermediate host and primary host at the following larval stages respectively:

Which of the following constitutes the correct pairing?

Cysticercus of $Taenia$ develops in

One example of animals having a single opening to the outside that serves both as mouth as well as anus is

Triploblastic acoelomate animals are