D. She wants Fern to still be able to see Wilbur after he is sold.
In the book, Fern has grown attached to Wilbur and is heartbroken when she learns that Wilbur must be sold. Fern's mother knows that giving up Wilbur will be very hard for her, so she suggests that Uncle Homer becomes Wilbur's new owner. If Wilbur is living on Uncle Homer's farm, Fern will be able to see him regularly.
