This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics And Genetic Disorders, Subject name: Pediatrics
[{'content': 'Which of these chromosomal anomalies was the earliest to be described? \nSelect and explain. \nA. Trisomy 21, B. Trisomy 18, C. Trisomy 13, D. Turner syndrome', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C. Trisomy 13Trisomy 13 was first described by Thomas Bartholin in 1657; trisomy 18 was first described by John Hilton Edwards in 1960; trisomy 21 was first described by John Langdon Down in 1866; and Turner syndrome was first described by Henry Turner in 1938.', 'role': 'assistant'}]