Question

multiple choice question
what group contains 60,000 species, most of which are vertebrates?
chordates
platyhelminthes
echinoderms
arthropods

Explanation:

Chordates are a group that includes vertebrates (like mammals, birds, fish, etc.) and some invertebrates (like tunicates). There are about 60,000 species of chordates, and the vast majority are vertebrates.
Platyhelminthes are flatworms (e.g., planarians, tapeworms), they are invertebrates and not a group with 60,000 species mostly vertebrates.
Echinoderms (e.g., starfish, sea urchins) are invertebrates.
Arthropods (e.g., insects, crustaceans) are invertebrates.

Answer:

Chordates