Parapodia are present in class
A. Polychaeta
B. Oligochaeta
C. Hirudinea
D. Archiannelida

Hint: The structures that are mostly found in the marine gastropods are the Parapodia, which act as a foot that bears the lateral projections. They are commonly present in a particular class that includes sand worms, tube worms, and clam worms, which are included in the phylum Annelida.

Complete answer:
The class which includes the bristle worms is the Polychaeta, which includes the class of annelid worms that are mostly marine. These organisms include the body segment, which has a pair of fresh protrusions called parapodia that bear many bristles that are made up of chitin. The polychaetes occur throughout the Earth's oceans at all depths, from forms that live as plankton near the surface.

The segments of the worms are usually brightly coloured, and luminescent, which is likely to bear a pair of paddle-like and highly vascularized parapodia, which are used for movement. It also acts as a primary respiratory surface. Bundles of bristles or the chaetae are said to be projections from the parapodia.

These parapodia are predominantly found in the phylum of annelids. These can be either paired, un-jointed with the presence of lateral outgrowths that bear the chaetae. These structures are commonly found in several groups of sea snails and sea slugs, 'parapodium' refers to lateral fleshy protrusions Polychaeta.

The Oligochaeta is a subclass of phylum Annelida, which includes most of all earthworms. The segmented parasitic or predatory worms that belong to the phylum Annelida. The Haplodrili are the primitive polychaete worms, which make use of cilia for their locomotion.

Hence, the correct answer is option (A).

Note: Parapodia are the matched extremities that are along the side present in the body fragments of Annelids. The beefy distensions on the sides of some marine gastropods are additionally called parapodia. They are very much evolved in ocean butterflies. Some ocean rabbits utilize their parapodia to swim.