No new substance is produced.
Answer:
a. amygdala
Explanation:
According to my research on studies conducted by various neurologists, I can say that based on the information provided within the question the part of the brain that was most likely under investigation in this study was the amygdala. This can be said because the amygdala is the part of the brain that is responsible for emotions, survival instincts (which dictates fear levels), and memory.
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I believe that it is the old growth not sure which one but between B and D I would go with B but I am not sure (hope I helped in some way )
