The correct answer is option 'C': Nereis and Pseudopodia.

Nereis is a type of marine worm, commonly known as a ragworm or clamworm. It belongs to the phylum Annelida. Nereis has well-developed parapodia, which are fleshy appendages that aid in locomotion. These parapodia contain many setae (bristles) that help the worm in crawling and burrowing through the substrate. The movement of Nereis is not facilitated by pseudopodia.

Pseudopodia, on the other hand, are temporary cytoplasmic extensions that are used for locomotion in certain organisms such as amoebas. These extensions are created by the flowing and rearrangement of the cytoplasm, allowing the organism to move by extending and retracting the pseudopodia. Pseudopodia are not found in Nereis or any other members of the phylum Annelida.

To summarize:

- Euglena: It is a single-celled protist that possesses a flagellum for locomotion. The flagellum is a long whip-like structure that beats to propel the organism through water.

- Paramecium: Paramecium is also a single-celled protist, but it moves using numerous tiny hair-like structures called cilia. The coordinated beating of these cilia allows the organism to move in a characteristic spiral or tumbling motion.

- Nereis: Nereis is a marine worm belonging to the phylum Annelida. It uses well-developed parapodia with setae for locomotion. The parapodia and setae enable the worm to crawl and burrow through the substrate.

- Starfish: Starfish, or sea stars, have tube feet that aid in locomotion. These tube feet are small, flexible, and suction-cup-like structures located on the undersides of the starfish's arms. By extending and retracting these tube feet, the starfish can move and grip onto surfaces.

In conclusion, the pair that is not correctly matched is Nereis and pseudopodia. Nereis does not use pseudopodia for locomotion; instead, it uses parapodia with setae.