Before the opening of the Amazon Go store, Amazon needed to do some research on what products consumers want to see offered in the store, what store features consumers want to see, what changes would need to be made to the store prototype to optimize sales, and how to price items to protect Amazon's brand image $($same prices as online or more or less expensive$).$ Which of the three r$\text{'}$s of marketing is Amazon focused on in this stage of development?