Which of the following scenarios best illustrates a shift in the Production Possibilities Curve (PPC) due to increasing returns to scale while also demonstrating comparative advantage?

A shift in the Production Possibilities Curve (PPC) happens when an economy can produce more goods efficiently, often due to improvements like better technology or resources. When we talk about increasing returns to scale, it means that as a company or economy produces more, the cost per unit decreases and efficiency increases. For example, imagine a country that specializes in producing cars and trains, and as it builds more factories, it becomes cheaper and faster to make both. If this country can produce cars more efficiently than another country, it shows comparative advantage, meaning it should focus on cars while trading for trains with the other country. This scenario illustrates how the PPC shifts outward because of increased production efficiency and specialization.