Q. A second-year medical student is reviewing metabolism pathways for her biochemistry midterm. She comes across the sorbitol pathway and learns that while many tissues can convert glucose to sorbitol via aldose reductase, only a few can further metabolize sorbitol to fructose using sorbitol dehydrogenase. Curious about this, she delves into the specifics, trying to identify which organs have both enzymes and thus can complete the conversion of glucose to fructose via the sorbitol intermediate. Which of the following organs has the ability to do both reactions?