The USDA defines food deserts as areas where there is limited access to affordable and healthy food, particularly for low-income populations. The correct options based on this definition are:
- in rural areas living more than 10 miles away from a grocery store.
- in urban areas living further than 0.5 mile away from a grocery store.
These definitions align with the USDA's criteria for determining food deserts based on distance and income levels. The other options do not accurately reflect the USDA's definition.