If she likes Velázquez, going to El Prado is a good idea. It's a Spanish museum, so Velázquez as a Spanish painter has several artworks displayed there, like Las Meninas. The other options don't work as well; B works better if she liked Miguel de Cervantes, C doesn't work because why would she go to Paris, and D doesn't work because Gaudí is a separate artist altogether.
So the answer is Organicé un día por La Ruta de Sancho Panza.
