The answer will be the reduction of unemployment. An increase in the capital stock and advance in technology will both cause production possibilities increase and make the production potentials curve shift outward. When the number of labor force increases, economy possibilities to produce goods and services will increase too therefore the production potentials curve shift outward. When the amount of labor forces increases if there is unemployment in an economy, it means that it has not use all of possibilities such as natural resources, work force, capital stock, technology etc. Furthermost, in the reduction of unemployment rate means that economy can deal with its possibilities more or perfectly and the option does not shift production possibilities frontier outward.