Laurer's canal is found in

Consider the following characters $:-$
$1.$ Bilateral symmetry
$2.$ Acoelomate
$3.$ Incomplete digestive system
$4.$ Mostly endoparasites
Select the correct group of phylum with its corresponding animal for the above-given characters $:-$

The animal group that is acoelomate is:

The first animal phylum to exhibit a triploblastic body organization is .........

Rhabdites occur in

The study of worms causing parasitic infestation in humans is known as: