Assertion :Hydrozoa have calcareous spicules. Reason: Porifera always contain sponges.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

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Assertion is correct but Reason is incorrect.

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Assertion is incorrect but Reason is correct.

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Solution

The correct option is D Assertion is incorrect but Reason is correct.
Hydrozoa is a taxonomic class of individually very small, predatory animals; Some are solitary and some colonial, most live in salt water and calcareous spicules are absent in these organisms.
Phylum Porifera will always contain sponges. Calcareous sponge contains calcareous spicules made up of calcium carbonate Hence, option D is correct.

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