This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S., Subject name: Medicine
Flapping tremors occurs in all EXCEPT: 
Select and explain. 
A. Uremic encephalopathy, B. Parkinsonism, C. Hepatic encephalopathy, D. CO 2 poisoning
B: Parkinsonism
Answer: B: Parkinsonism 
Explanation: ANSWER: (B) ParkinsonismREF: Harrison's 18th ed various chaptersAsterixis (also called the flapping tremor, or liver flap) or wing beating tremorTremor is of 2-3 second cycleSeen in uremic, hepatic, metabolic encephalopathyC02 retentionAlcohol intoxicationSome Important tremors:Intention tremor: cerebellar dysfunctionResting tremor or pin rolling tremor: parkinsonismEssential tremor (sometimes called benign essential tremor) is the most common type of tremorOrthostatic tremor is characterized by fast {>12 Hz) rhythmic muscle contractions that occur in the legs and trunk immediately after standing seen along with essential tremorPhysiologic tremor occurs in every normal individual and has no clinical significance. It is rarely visible and may be heightened by strong emotion (such as anxiety or fear), physical exhaustion, hypoglycemia, hyperthyroidism, heavy metal poisoning, stimulants, alcohol withdrawal or fever.