Notice what the D and the L mean is these will be mirror images with respect to one another. These are known as enantomers. So sugars that are mirror images of one another are known as enantomers. And so if we draw a line, this will be a mirror image of this molecule. And so these oh groups, which point to this side, will point onto the opposite side on this molecule here. And so in the deisomer, we see that this green hydroxyl group, which is the hydroxyl group that is found on the stereogenic carbon, that is far less away from this aldehyde group.