Interactive Reading

Read the passage and answer the question.

Octopuses are among the most intelligent animals without a backbone. Each of their eight arms contains its own cluster of nerve cells, allowing the arm to taste, touch, and react somewhat independently of the brain. This means an octopus can explore a crevice with one arm while the rest of its body attends to something else. In experiments, octopuses have opened jars, solved mazes, and even recognized individual human caretakers. Yet they live only a few years, and they are mostly solitary, which makes their rapid learning all the more surprising to the scientists who study them.