The question I want you to answer is: which chiral centers have different chirality in D-glucose as compared to L-gulose. To give you an idea of what I'm asking, compare the chirality at carbon 2, 3, and 4 in D-glucose to the chirality at carbon 2,3, and 4 in D-idose. You'll see that they're opposite at carbon 2; they're the same at carbon 3; and they're the same at carbon 4. So the only difference is at carbon 2. So I'm asking you to perform the same analysis, but this time comparing D-gluocse to L-gulose. You can see D-gulose on the chart; L-gulose has the opposite chirality from it.