Final answer:
The image will appear underexposed due to decreased density.
Step-by-step explanation:
The image will appear underexposed due to decreased density.
When using the AEC (Automatic Exposure Control) setting, the X-ray machine automatically adjusts the exposure time based on the detected radiation passing through the patient's body. Selecting only the center cell for a PA chest means that only a small portion of the X-ray beam is passing through the patient, resulting in a lower overall density in the image. As a result, the image will appear underexposed.