For optimal conditioning, the minimum delay between the cs and us should be

Plastic and steel are substitutes in the production of body panels for certain automobiles. if the price of plastic increases, with other things remaining the same, we would expect: a) the demand curve for plastic to shift to the left. b) the price of steel to fall. c) the demand curve for steel to shift to the left d) nothing to happen to steel because it is only a substitute for plastic. e) the demand curve for steel to shift to the right