D
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Make a list from most to least important
I don't think you mean above the medula oblongata, i think you mean something else because the connection between the two hemispheres is connected by the Corpus Callosum which is above of the thalamus.
The only answer that i can make sense of what you've wrote is A Cerebellum but i don't think you are correct forming your question. Where did you find the question
If I'm not mistaking, it's heterozygous, What are your options
