The correct option is B Prawn, Scorpion, Locusta
Earthworm is an annelid while pinworm is nematode and tapeworm is platyhelminth.
Sponges belong to the phylum Porifera, sea anemone belongs to phylum Cnidaria while starfish to Echinodermata.
Plasmodium falciparum is a malarial parasite belonging to the Apicomplexa, Amoeba is protozoa while the mosquito is an arthropod.
Prawn, Scorpion, Locusta all belong to the phylum Arthropoda.
Therefore, the correct answer is option B.