A diagnosis of Parkinson's disease is made based on the presence of which of the following symptoms? (Select all that apply.)

A. Resting tremor: A classic feature of Parkinson’s disease, the resting tremor typically begins unilaterally and is most noticeable when the muscles are relaxed. It often presents as a “pill-rolling” motion of the fingers and diminishes during purposeful movement. B. Rigidity: Muscle stiffness or rigidity is another hallmark of Parkinson’s disease, resulting from increased muscle tone and resistance to passive movement. This symptom contributes to discomfort, limited mobility, and the characteristic stooped posture seen in affected individuals. C. Bradykinesia: Slowness of voluntary movement, or bradykinesia, is a defining symptom of Parkinson’s disease. It manifests as difficulty initiating movement, reduced facial expression, and decreased arm swing during walking, significantly impacting daily activities. D. Progressive decline in cognitive function: Cognitive decline may develop in the later stages of Parkinson’s or in Parkinson’s disease dementia but is not part of the initial diagnostic criteria. The diagnosis primarily relies on motor symptoms rather than early cognitive changes. E. Orthostatic hypotension: This condition can occur as a secondary autonomic effect of Parkinson’s disease or its medications, but it is not a core diagnostic feature. It supports disease progression rather than confirming the initial diagnosis.