The correct answer is option 1, Asterias. Asterias, commonly known as the starfish, exhibits bilateral symmetry in its body organization. Bilateral symmetry means that the body can be divided into two equal halves along a single plane. This symmetry allows for more advanced movement and coordination.

Option 2, sea anemone, does not have bilateral symmetry. Sea anemones have a radial symmetry, meaning their body parts are arranged around a central point, like the spokes of a wheel.

Option 3, Nereis, also does not have bilateral symmetry. Nereis is a type of polychaete worm that has a segmented body and lacks bilateral symmetry.

Option 4, Euchinus, is an incorrect spelling and is not a recognized organism. Therefore, it cannot be determined whether it has bilateral symmetry or not.

In conclusion, only option 1, Asterias, has bilateral symmetry in its body organization.