Final answer:
b) Left posterior oblique (LPO)
The Left Posterior Oblique (LPO) projection is optimal for demonstrating an injury to the right anterior ribs as it provides a clear view by projecting the anterior ribs away from the image receptor.
Step-by-step explanation:
To optimally demonstrate an injury to the right anterior ribs, the best projection would be the Left Posterior Oblique (LPO) position. The LPO view is an oblique radiographic projection that will best visualize the anterior aspects of the ribs, specifically on the side opposite the direction of the oblique. In this position, the right anterior ribs are more prominently displayed as they are farther away from the image receptor and less superimposed by other structures, thereby providing a clearer image of any potential injuries. An alternative projection to consider, if the patient's condition allows, is the Anteroposterior (AP) projection for bilateral ribs; however, the oblique LPO is preferred to isolate the anterior ribs on the right side. The right anterior oblique (RAO) would project the left anterior ribs, and the left lateral decubitus position is typically used to demonstrate free air or fluid levels.