This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parkinsonism, Subject name: Medicine
Earliest feature of parkinsonism? 
Select and explain. 
A. Anosmia, B. Rigidity, C. Postural instability, D. Freezing
A: Anosmia
Answer: A: Anosmia 
Explanation: Ans. (a) AnosmiaRef: Harrison 19th ed. / 2609Non-motor symptoms may precede motor symptoms of Parkinsons diagnosis by years. The most recognizable early symptoms include:* Loss of sense of smell, constipation* REM behavior disorder* mood disorders* Orthostatic hypotensionSubsequently Motor Features Appear1. Tremors (resting 4-6 Hz)2. Rigidity3. Bradykinesia4. Good Response to levodopa