A nurse is caring for a client who reports to the clinic for laboratory tests. The client has an acute kidney injury caused by acute tubular necrosis and asks why their glomerular filtration rate keeps decreasing. Which of the following pathophysiological changes occurring in the kidney should the nurse explain as the cause of the decrease?

A. Injury to renal tubular cells occurs in ATN, but the primary cause of decreased GFR is related to blood flow, not just tubular injury. B. Inflammatory cell invasion is more characteristic of interstitial nephritis, not the primary cause of GFR decrease in ATN. C. A reduction of blood flow to the kidneys (ischemia) causes decreased perfusion pressure, leading to reduced GFR, which is the main reason for GFR decline in ATN. D. Obstruction causing backflow is seen in post-renal causes of AKI, not typical in ATN.