What does a sandworm (Nereis) possess for locomotion?

$A$: True coelom originated for the first time in phylum $Annelida$.
$R$: It allowed the animal to have an alimentary canal longer than the body and space for storing gametes.

Read the following four statements $(A-D)$:
$(A)$ Annelids possess only longitudinal muscles which help in locomotion.
$(B)$ Nephridia do not help in excretion and osmoregulation.
$(C)$ Closed type circulatory system is present in most of annelids.
$(D)$ Members of phylum Annelida are triploblastic,metamerically segmented,and acoelomate.
How many of the above statements are incorrect?

$A$: Annelids exhibit metameric segmentation.
$R$: The body of an annelid is divided into two equal halves by a single plane.

The first true organ system grade of body organization is developed in:

The body is segmented in: