The outward shift to the production possibility curve could be due to

An outward shift in the production possibility curve occurs when a country is able to produce more goods and services with the same resources it had before. Economic growth is the most likely cause of this shift. When a country experiences economic growth, it means that it is producing more goods and services and generating more income. This can be due to various factors, such as increased productivity, new technologies, improved infrastructure, increased investment, or better education and health among the population. As a result of this growth, the country can produce more goods and services, leading to the outward shift in the production possibility curve. Therefore, the correct answer is "economic growth".