Final answer:
The sense of smell (olfaction) is the one that is not routed through the thalamus, as it is sent directly to the olfactory cortex, unlike other sensory modalities.
Step-by-step explanation:
The sense that is not routed through the thalamus is B. smell.
Within the human sensory system, five major senses are recognized: hearing, sight, taste, touch, and smell. Except for olfaction (smell), all sensory signals are primarily routed through the thalamus to the cortex for processing. Olfactory information bypasses the thalamus and is sent directly to the olfactory cortex. This is distinct from the other senses, such as audition (hearing), gustation (taste), and vision, which do involve the thalamus in their synaptic pathways.
The function of the thalamus as a relay station for sensory information is crucial for integrating and processing sensory data before it reaches the cortex.