In the long run, potential growth in the economy and a rise in real GDP per capita might occur from all of the following except growth in population.
While a growing population can contribute to economic growth, it does not necessarily lead to an increase in real GDP per capita, as it may result in a dilution of resources or a lower standard of living if not accompanied by corresponding increases in productivity or economic output. The other options (an increase in government spending on public goods, an increase in savings, and an achievement in technological progress) are generally seen as factors that promote productivity and economic growth, thus contributing to an increase in real GDP per capita.