A. A middle-aged patient admitted with depression: Depression has no physiological effect on the accuracy of pulse oximetry readings. B. A teenager with brightly painted fingernails: Nail polish, especially dark or bright colors, can interfere with the infrared light used by pulse oximeters and give false readings. C. An older adult diagnosed with dementia: While dementia may make cooperation with the procedure difficult, it doesn’t directly affect the accuracy of the reading. D. A toddler with a fever of 100.2° F: A mild fever does not directly interfere with pulse oximetry accuracy.