Final answer:
A shift rightward of the production possibilities frontier can be caused by an increase in resources and technological progress.
Step-by-step explanation:
A shift rightward of the production possibilities frontier (curve) can be caused by an increase in resources and technological progress. Both factors contribute to an expansion of a country's production capacity.
For example, if a country discovers new oil reserves or increases its labor force, it will have more resources available for production. Similarly, advancements in technology can lead to increased efficiency and productivity, allowing for greater output.