Several factors have contributed to economic growth in some or all countries: (1) growth in the quantity and quality of _____________ resources used (human capital); (2) increase in the use of inputs provided by the _____________ (natural resources); (3) growth in physical _____________ inputs (machines, tools, buildings, inventories); and (4) _____________ advances

(new ways of combining given quantities of labor, natural resources, and capital inputs) allowing greater output than previously possible.