Organelle,The primary role of the flagellum is locomotion but it also often has function as a sensory organelle, being sensitive to chemicals and temperatures outside the cell. Flagella are organelles defined by function rather than structure.
Echinoderms, like chordates, are deuterostomes and are therefore thought to be the most closely related of the major phyla to the chordates
The correct answer among the choices provided is option A. Lung capillaries are responsible for exchanging carbon dioxide for oxygen from the air. Blood that comes from the heart gets oxygen from the alveoli. The carbon dioxide in the blood goes into the alveoli at the same time.
