Question

1. which trait is characteristic of invertebrates?

they are immobile.
they have a spinal column.
they have no defined organ systems.
they have bilateral symmetry.

Explanation:

Invertebrates are animals without a backbone (spinal column). Many invertebrates are mobile (e.g., insects can fly, mollusks can move). Most invertebrates have defined organ systems (e.g., digestive, circulatory in some). Bilateral symmetry (where the body can be divided into two mirror - image halves along one plane) is a common trait among invertebrates. For example, arthropods (insects, crustaceans), annelids (earthworms) have bilateral symmetry.

Answer:

They have bilateral symmetry.