The question was not that deep

What helped me was that the guarantee was only for MOST nurseries, so Wally's could be a part of the minority of Nurseries not talked about in the stim

The reason I presumed C was wrong was because if coffeehouses and restaurants (Public Places) are well designed, then ALL, not most, of those well-designed places will feature Artworks as stated in the stimulus. Not sure if I am over-generalizing though...