Answer:A .buy only sneakers
Explanation: The MRS for sneakers is 3 and Shoes is 4, meaning sneakers is of higher MRS than shoes. Also meaning that, sneakers are originally expensive or costly than shoes. If the price of both item have risen, it simply stand to reason that his attachments for sneakers will equally be higher as against the shoes. Meaning, he will demand for sneakers will increase and he might eventually stick to buying only sneakers.