One explanation for why our sense of smell and language are so disconnected is that A. smell is only of secondary use to humans, language is of primary use.
B. olfactory information is not integrated in the the thalamus prior to processing in the cortex, and the two systems are primarily processed in opposite hemispheres.
C. there is no need to have connections between smell and language.
D. language developed much earlier in evolution than smell.
E. olfactory information is more widely distributed throughout the brain than is language.

B. olfactory information is not integrated in the thalamus prior to processing in the cortex, and the two systems are primarily processed in opposite hemispheres.

Explanation:

The thalamus is the main source of sensory information to the primary sensory cortex except for the sense of smell. The olfactory information from the sensory neurons needs to pass through the thalamus in order to reach the primary sensory cortex. Moreover, different thalamic nuclei, i.e., different groups of packed neuronal cell bodies that form the thalamus, have been involved in language. A bilateral thalamic activation (with left greater than right thalamic activation), as well as the activation of cortical regions associated with the language, is observed during tasks related to language processing. Language information is processed within the left hemisphere, while the olfactory information is processed in the olfactory bulb which is located on the inferior (bottom) side of the cerebral hemispheres.