Joe's Bar and Grill uses two inputs, beer and pretzels. When the price of beer was $10 a case and the price of pretzels was $20 a case, Joe used 1 case of beer and 2 cases of pretzels a day. When the price of beer was $20 a case and the price of pretzels was $10 a case, Joe used 2 cases of beer and 1 case of pretzels a day. Joe produced the same output in each of these circumstances. From this information, we can conclude:
A.
Joe has a constant returns to scale production function.
B.
Joe has a cost function that exhibits increasing returns.
C.
Joe is not minimizing costs.
D.
Joe's behavior is consistent with profit maximization.
E.
Joe's production function exhibits diminishing marginal product.