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': 'With respect to their permanent successors, the sum\nof the mesio-distal diameters of the first and second deciduous molars is generally: \nSelect and explain. \nA. Less, B. Greater, C. The same, D. Not related', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Leeway space\nLeeway space is the difference between the sum of the mesiodistal widths of the primary canine, first and second molars to permanent canine, first and second premolars. The unerupted canine, premolars are on an average 1.7 mm smaller per quadrant in the lower arch and 0.9 mm per quadrant in the upper arch.', 'role': 'assistant'}]