This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'Total space analysis by Merrifield requires: \nSelect and explain. \nA. Study cast and radiograph, B. Study cast and reference table, C. Study cast and cephalogram, D. All of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Total space analysis by Merrifield;\n\nRequires study casts and cephalograms.\nDivides the lower arch into anterior, middle and posterior areas.\nThe discrepancy for each area is calculated and the resultant value is added to yield the total discrepancy of the arch.\n\nTotal space analysis as described by Merrifield is divided into three parts anterior, midarch and posterior.\nThis is done for simplicity in identifying the area of space deficit or surplus, as well as accuracy in differential diagnosis.\nRef: Graber 6th edition', 'role': 'assistant'}]