Subject: Animals, Animal Classification.
Clams, snails, and oysters are mollusks, part of the phylum Mollusca.
Mollusca is the second-largest phylum of invertebrates, after Arthropoda.
Mollusks have three defining characteristics:
• A ,mantle,, used for breathing and excretion.
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• A ,radula,, used for feeding
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• A particular structure of the nervous system,, with two cords of paired ganglia.
There are 10 main classes of mollusks, seven living and three extinct:
• Gastropoda,: ,snails, and slugs.
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• Bivalvia,: ,clams, oysters,, etc.
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• Polyplacophora,: chitons.
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• Cephalopoda,: squids, octopuses, nautiluses, etc.
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• Scaphopoda,: tusk shells
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• Cricoconarida, (extinct)
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• Aplacophora
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• Monoplacophora
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• Rostroconchia, (extinct)
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• Helcionelloida, (extinct)
This means A) Mollusks is the right answer.