Questions: Most chordates and vertebrates exhibit a notochord bilateral symmetry radial symmetry

The answer is the first one: a notochord.

Explanation for each option:

1. A notochord: This is correct. Most chordates and vertebrates exhibit a notochord at some stage of their development. The notochord is a flexible, rod-shaped body that provides support. In vertebrates, it is usually replaced by the vertebral column during development.

2. Bilateral symmetry: This is also correct. Most chordates and vertebrates exhibit bilateral symmetry, meaning their body can be divided into mirror-image halves along a single plane.

3. Radial symmetry: This is incorrect. Radial symmetry is characteristic of organisms like cnidarians (e.g., jellyfish) and echinoderms (e.g., starfish) but not chordates or vertebrates.

Summary: Most chordates and vertebrates exhibit a notochord and bilateral symmetry, but not radial symmetry.