Read this and answer the question. If the question is unanswerable, say "unanswerable".

Apple has generally dominated the premium PC market, having a 91 percent market share for PCs priced at more than $1,000 in 2009, according to NPD. The Macintosh took 45 percent of operating profits in the PC industry during Q4 2012, compared to 13 percent for Dell, seven percent for Hewlett Packard, six percent for Lenovo and Asus, and one percent for Acer. While sales of the Macintosh have largely held steady, in comparison to Apple's sales of the iPhone and iPad which increased significantly during the 2010s, Macintosh computers still enjoy high margins on a per unit basis, with the majority being their MacBooks that are focused on the ultraportable niche that is the most profitable and only growing segment of PCs. It also helped that the Macintosh lineup is simple, updated on a yearly schedule, and consistent across both Apple retail stores, and authorized resellers where they have a special "store within a store" section to distinguish them from Windows PCs. In contrast, Windows PC manufacturers generally have a wide range of offerings, selling only a portion through retail with a full selection on the web, and often with limited-time or region-specific models. The Macintosh ranked third on the "list of intended brands for desktop purchases" for the 2011 holiday season, then moved up to second in 2012 by displacing Hewlett Packard, and in 2013 took the top spot ahead of Dell.

Which of Apple's products is focused on the ultraportable niche of PC's?
MacBooks