A) Unipolar neuron - spinal cord - medulla oblongata - pons - midbrain - thalamus - parietal lobe
B) Unipolar neuron - spinal cord - reticular formation - hypothalamus and limbic system
C) Unipolar neuron - spinal cord - medulla oblongata - pons - midbrain - parietal lobe
D) All of these answers are correct.