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: Surgery
All of the following areas are commonly involved sites in pelvic fracture except: 
Select and explain. 
A. Pubic rami, B. Alae of ileum, C. Acetabula, D. Ischial tuberosities
D: Ischial tuberosities
Answer: D: Ischial tuberosities 
Explanation: Fracture of the ischial tuberosity is uncommon injury. Ref: Skeletal Radiology - Volume 30, March 2001; Examination of Musculoskeletal Injuries eBook w/Web Resource By Sandra Shultz, Peggy Houglum, David Perrin, 3rd Edition, Page 495