Vertebrates have a:

**The reasoning** The word "vertebrate" comes from *vertebrae* — the individual bones that make up the **backbone** (also called the spinal column). This is THE defining feature of vertebrates. All vertebrates — from fish to birds to humans — have an internal skeleton with a backbone protecting their spinal cord. It's what separates them from invertebrates (animals without backbones, like insects and jellyfish). **Why the wrong options tempt you** - **A) Hood** — Cobras have hoods, but not all vertebrates do. This confuses a feature of *one species* with the group's defining trait. - **C) Shell** — Turtles and tortoises have shells, but they're still vertebrates *because* they have backbones underneath. Shells aren't universal to the group. - **D) Wings** — Only birds and bats (among vertebrates) have wings. Fish and snakes are vertebrates too, and they definitely don't fly! **Quick takeaway** If it has a **backbone**, it's a vertebrate — that's the one feature every single member shares, from tilapia to eagle to human.