Final answer:
Flexing the fingers in a PA projection of the wrist brings the carpals in closer contact with the image receptor, helping to produce a clearer and more accurate radiograph for diagnosis.
Step-by-step explanation:
The purpose of flexing the fingers in a PA projection of the wrist is C) It brings the carpals in closer contact with the image receptor. When the fingers are flexed, this position tends to flatten the carpal bones against the image receptor, creating a clearer image for diagnosing conditions such as fractures or carpal tunnel syndrome. Proper positioning is essential to ensure that the carpal bones, particularly the scaphoid, are clearly visualized without overlap. Consequently, this positioning minimizes the occurrence of any distortion and provides a true representation of the carpal bones in the wrist radiograph.