<span>When contaminated shellfish is consumed, it can cause Neurotoxic Shellfish Poisoning</span>
I am not sure but I think the answer would be A. Since where they live caused them to need to adapt.
Sorry but it's hard to see
<span>The vertebrate nerve code is found dorsally while that of the crayfish is located ventrally of its body. Additionally, the ventral nerve cord of the crayfish is a solid ventral tube while that of the vertebrate is a hollow tube. All vertebrates are chordates, the dorsal nerve cord develops into nervous tissue of the brain and spinal cord; unlike the notochord which is the scaffolding for development of the bone and cartilage of the vertebral column. In the crayfish, they have a ventral nerve cord which is a collection of nerves found in the abdomen.</span>
