Why molluscs are considered advanced over annelids?

(i) Why molluscs are considered advanced over annelids?
(ii) Justify that annelids are evolutionary precursors of molluscs.

(i) The molluscs have advancement over annelids, as they have distinct head, better sense organs and gills or lungs for respiration.
{ii) Annelids are considered evolutionary precursors of molluscs as they do not have metameric segmentation. However, Neopilina a living fossil shows metameric ’ segmentation. Besides, its trochophore larva, it has structural similarities to annelid trochophore larva. These two evidences suggest that molluscs have descended from annelids.