A Country Produces Bread and Cheese Using Only Labor as Input

A country produces bread and cheese using only labor as input. The production possibility frontier of the country represents the:

A) amount of bread that can be produced using all the labor.
B) amount of cheese that can be produced using all the labor.
C) minimum amount of bread and cheese that can be produced using all the labor.
D) maximum amount of bread and cheese that can be produced using all the labor.