Spiders belong to the phylum

Mollusca
Annelida
Cnidaria
Arthropoda

The correct answer is D. Arthropoda.

Arthropods are a phylum of animals that have jointed legs and a hard exoskeleton. They are the most diverse phylum of animals, with over 1.5 million known species. Spiders are arthropods, as are insects, crustaceans, and millipedes.

Mollusks are a phylum of animals that have a soft body and a hard shell. They include snails, clams, and octopuses.

Annelids are a phylum of animals that have a long, segmented body. They include earthworms, leeches, and marine worms.

Cnidarians are a phylum of animals that have a radial body plan and stinging tentacles. They include jellyfish, corals, and sea anemones.