Which of the following is an acoelomate animal with a protandrous nature?

During its life cycle,the liver fluke ($Fasciola$ $hepatica$) infects its intermediate host and primary host,respectively,through which of the following larval stages?

Which structure is found in the phylum Platyhelminthes to attach to the host?

What do Platyhelminthes exhibit in contrast to Annelids?

What is observed in Platyhelminthes,in contrast to Annelida?

How many intermediate hosts do trematode parasites require to complete their life cycle?