Final answer:
c. Angle the tube cephalad
To project the clavicles above the lung apices when a patient cannot be arranged in a lordotic position, the X-ray tube should be angled cephalad.
Step-by-step explanation:
If the patient cannot be placed in a lordotic position to image the apices of the lungs, the best adjustment to make is to angle the tube cephalad. This means to angle the X-ray tube head upward toward the patient's head, which causes the clavicles to project higher on the image and clears the view of the lung apices. Angling the tube cephalad compensates for the lack of lordotic positioning, which is normally used to lift the clavicles above the lung apices. Adjusting the Source-to-Image Distance (SID) would not serve the same purpose.