This is a wholesaling business, or answer B. To buy at a wholesale price means to buy it directly from the factory at cost or with minimal markup. This is often what happens between manufacturers and other companies - such as Bath and Body Works or Bed, Bath, and Beyond.
They buy from a manufacturer for a low cost and then mark the price up some to make a profit when they sell it in stores. It kind of makes you wonder what their buying the products at to make the price they sell it at worth it to them.
It also makes me wonder why in the world Apple charges so much for their phones when they’ve changed so slightly since the iPhone 7… but that’s my opinion.