Answer:
In the group of a brain, motor neuron, glands, and stimuli, the glands can be considered as an odd one out.
It is because the brain, motor neuron, and stimuli come under a common biological system which is termed as a nervous system.
A nervous system is a network or complex of nerve cells that perform the function of transmitting nerve impulses from one body part to another.
It consists of a brain, spinal cord, and different types of nerve cells (such as sensory nerves, motor nerves et cetera).
In contrast, a gland is defined as an organ of cells which synthesize and release chemical substances (such as hormones, enzymes et cetera) either into the bloodstream (endocrine glands) or into the body cavities (exocrine gland).
Thus, the gland can be considered as the odd one out.
