Final answer:
The food worker should date mark the lasagna with the date seven days from the lasagna's preparation.
Step-by-step explanation:
The food worker should date mark the lasagna with the date seven days from the lasagna's preparation. This is because the proper date marking should be based on when the lasagna was made, not when the individual ingredients were cooked or opened. The lasagna is considered a new food item once it is prepared, so the seven-day date mark should start from that point. In food safety practices, it's crucial to appropriately date mark prepared items to ensure consumer safety. For the given scenario, the food worker should date mark the lasagna with the date seven days from its preparation (Option b). This approach considers the cumulative time since the ground meat was cooked and the ricotta cheese was opened, providing a clear guideline for the safe consumption of the lasagna. While the manufacturer's used-by date on the ricotta packaging is relevant for the cheese's quality, it does not account for the specific conditions and handling after opening, making the preparation date a more accurate indicator for overall freshness and safety.