In this particular case study a brand of chocolate bars had only one product in their store, in three different flavors, all with the same price point. So how do you offer an upsell when you just have one product in three flavors? On the homepage, all three products were mentioned. In the navbar, all three products were mentioned. Even on each PDP the other two flavors were mentioned.
The idea for this test was that when a customer added one of these to cart, the upsell offered a single pack of another flavor for $6 (B and C). That’s it, you can only add 1 of the alternate flavor, but you get a slight discount on it. The two variations were functionally similar but had slightly different designs were tested.