An economy produces two categories of output: Digital Services and Agricultural Goods. The diagram below shows a shift in the economy's production possibility frontier (PPF) from PPF1\text{PPF}_1PPF1 to PPF2\text{PPF}_2PPF2:
Which of the following events is most likely to have caused this shift?
An increase in the net migration of high-skilled software developers into the country.
A significant technological innovation in automated crop-harvesting equipment.
A decrease in the central bank's base interest rate, which stimulates consumer spending.
A nationwide retraining program that redirects agricultural workers into high-tech services.
