A nurse is reviewing provider prescriptions for a client who has reduced kidney function. Which of the following prescribed diagnostics should the nurse question?

A. A CT scan with contrast uses iodinated contrast dye, which can be nephrotoxic and worsen kidney function. This prescription should be questioned or done with caution in clients with reduced kidney function. B. MRI of the abdomen typically uses gadolinium-based contrast, which is generally safer but still used cautiously; however, MRI without contrast is often safe. C. A KUB radiograph is an X-ray without contrast and is safe for clients with kidney impairment. D. A renal ultrasound is a non-invasive, contrast-free diagnostic tool and is safe for clients with reduced kidney function.