A"universal product code" (upc): 1. was required by the federal fair packaging and labeling act. 2. slows down the retail checkout process. 3. all of the above are true. 4. involves placing the price per ounce on or near the product. 5. identifies a product with a mark which can be "read" by electronic scanners.

5. Identifies a product with a mark which can be "read" by electronic scanners. UPC is a machine scannable bar code that's used in the United States, Canada, United Kingdom, and many other countries for tracking items in stores. The very first UPC marked item scanned at a retail checkout was a10-pack of Wrigley's Juicy Fruit chewing gum on June 26, 1974. This item was put on display in the Smithsonian National Museum of American History in Washington, D.C. With that in mind, let's look at the options and see what does or does not make sense. 1. Was required by the federal fair packaging and labeling act. * Since this act requires "consumer commodities" to be labeled with their identity, name & place of manufacturer, and its quantity, this is far more information than a 10 digit code can encode. So this answer is wrong. 2. Slows down the retail checkout process. * If the UPC code slowed things down, that would increase the cost to the retailers for no gain. In fact, the use of the UPC has reduced checkout times and has improved accuracy. So this choice is also wrong. 3. All of the above are true. * Since the above 2 are wrong, so is this. 4. Involves placing the price per ounce on or near the product. * The UPC identified what the item is. The price doesn't appear on the UPC. So this too, is wrong. 5. Identifies a product with a mark which can be "read" by electronic scanners. * This is exactly what the code does. So this is the correct choice.

Dwould be the correct answer to this problem

Maximizing the difference between total revenue and total cost;