Concept:The cortex is the outer layer of a mammalian kidney, located just beneath the kidney capsule.Explanation:The diagram shows a mammalian kidney in longitudinal section.The cortex appears as the outermost region of the kidney.In the given diagram, this outer region is labelled I.Part I is therefore the cortex.The other labelled parts are inner structures of the kidney and are not the cortex.Answer:A. I
