Question

notochords are flexible, longitudinal rods between the digestive tract and the nerve cord. their main purpose is to support the digestive tract. pharyngeal slits can be found in the pharynx of humans and fish. what is the primary characteristic that all organisms within phylum chordata share? presence of wings for flight presence of a notochord presence of an exoskeleton

Explanation:

1. Analyze Option A: Wings for flight are not a universal feature of Chordata (e.g., fish, humans without wings don't have them for flight), so A is incorrect.
2. Analyze Option B: The text states notochords are a key feature of chordates (between digestive tract and nerve cord), and by definition, all Chordata have a notochord (at some life stage), so B is correct.
3. Analyze Option C: Exoskeletons are not a characteristic of Chordata (Chordates have endoskeletons or no hard outer skeleton like that; exoskeletons are in arthropods), so C is incorrect.

Answer:

B. presence of a notochord