Answer:
Option (e).
Explanation:
Nervous system is one of the most important systems of the organism that helps them to respond them towards the environment. The nervous system includes the brain, spinal cord and all the neurons.
Nervous system is present in highly complex organism and increases in complexity in case of higher animals. Lower animals do not have nervous system but still they respond to their environment with the help of chemical and receptor. Hence, all the animals have the ability to respond towards the environment.
Thus, the answer is option (e).
