The difference between a straight-line production possibilities frontier and one that is concave is that:

The difference between a straight-line production possibilities frontier and one that is concave is that: the concave production possibilities frontier exhibits constant opportunity costs, while the straight line frontier does not. o the concave frontier reflects the problem of scarcity but the straight line frontier does not. o O the straight line frontier reflects constant opportunity costs but the concave frontier does not. neither the straight line nor the concave frontier reflect output limits.