This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Brainstem, cerebellum and ventricles, Subject name: Anatomy
A six-year-old girl has brief, irregular contractions in her feet; symptoms are suspected to be a result of an untreated strep infection. What is the diagnosis? 
Select and explain. 
A. Chorea gravidarum, B. Chorea major, C. Ballism, D. Sydenham chorea
D: Sydenham chorea
Answer: D: Sydenham chorea 
Explanation: Sydenham chorea (St. Vitus dance) - commonest chorea. occurs mainly in girls as a sequela to rheumatic fever. Chorea major (Huntington's disease) -inherited disorder manifests as choreiform movements and progressive dementia. Chorea gravidarum occurs during the 2nd trimester of pregnancy. Ballism and hemiballism -violent flinging movement of one or both extremities due to infarct of the subthalamic nucleus.