A
Anterior wall of the acetabulum
B
Posterior wall of the acetabulum
C
Lateral aspect of the obturator canal and quadrilateral plate
D
Iliopubic eminence
Explanation:Correct Option: C. The radiographic teardrop (U-figure) is a two-dimensional representation of a three-dimensional structure. Its lateral wall is formed by the medial wall of the acetabulum, while its medial wall is formed by the anteroinferior portion of the quadrilateral plate and the lateral wall of the obturator canal. It is used as a landmark for the inferior and medial limits of acetabular reaming. (Ref: Bowerman et al., Radiology, 1982)