It began 3.5 billion years ago
Answer:
Cerebellum
Explanation:
According to my research on studies conducted by various neurologists, I can say that based on the information provided within the question the doctors will likely find Christy's problem in the Cerebellum which is located in the Hindbrain. The Cerebellum is responsible for coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity. A problem with the Cerebellum can impair movements similar to what Christy is experiencing.
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I attached a picture showing how to do it