This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
[{'content': "French in Foley's Catheter refers to \nSelect and explain. \nA. Outer circumference measurement, B. Inner circumference measurement, C. Diameter of catheter, D. Lumen size", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) Diameter of catheterRef Internet Sources, Wikipedia* The French scale or French gauge system (most correctly abbreviated as Fr, but also often abbreviated as FR or F) is commonly used to measure the size (diameter) of a catheter.* 1Fr=0.33mm, and therefore, the diameter of the catheter in millimeters can be determined by dividing the French size by 3:# D(mm)=Fr/3 or# Fr = D (mm) x3For example, if the French size is 9, the diameter is 3mm.Note that the French scale is a measurement of the diameter, not the circumference (diameter xp).* An increasing French size corresponds to a larger diameter catheter. This is contrary to needle-gauge size, where the diameter is 1/gauge, and where the larger the gauge the narrower the bore of the needle.', 'role': 'assistant'}]