Why is the shape of the production possibilities frontier PP

Why is the shape of the production possibilities frontier (PPF) often curved instead of straight?

Solution

Option B

The shape of this production possibility frontier is due to increasing cost. As more of one product is produced, increasingly larger amounts of the other product must be given up. Some factors of production are suited to producing both the goods, but as the production of one of these commodities increases, resources better suited to production of the other must be diverted. Producers of good A are not necessarily efficient producers of good B, and producers of good B are not necessarily efficient producers of good A, so the opportunity cost increases as one moves toward either extreme on the curve of production possibilities.