Hello! The correct answer would be D. Cnidarians. :)
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Sponges absent
Cnidarians not jointed (Aquatic organisms, all have tentacles with nematocysts - stinging cells, used to capture food.)
Roundworms absent (AKA nematodes are unsegmented, colorless and do not have appendages).
Annelids not jointed (With the exception of leeches, all annelids have chitonous hair-like structures projecting from their cuticle. These appendages fulfill different functions in different species.)
Mollusks not jointed (Invertebrates that lack hard appendages such as legs or antennae)
Arthropods jointed (the arthropods are the only invertebrates to have jointed appendages)
Echinoderms not jointed (Due to their radial symmetry, all echinoderms have appendages which point outward from the center of the body like the spokes on a wheel.)
and vertebrate jointed
Answer:
one cell
Explanation:
Oogenesis takes place in the outermost layers of the ovaries, ultimately resulting in the production of one cell.
Birds have a hard time in cold weather, because their body temperatures are higher than those of humans They provide warmth and insulation against colder temperatures. Many birds grow extra feathers in the months leading up to colder weather, so that they'll stay warmer when temperatures drop.