Final answer:
The proper placement of the patient's arms for the upright, lateral projection of the chest is alongside the body.
Step-by-step explanation:
The proper placement of the patient's arms for the upright, lateral projection of the chest is alongside the body (option d). This position allows for a clear and unobstructed view of the chest in the X-ray. Placing the arms on the hips (option a), crossed over the chest (option b), or above the head (option c) could interfere with the accuracy of the image.