Investment spending primarily affects long-run aggregate supply by facilitating __________, which enhances productivity.

Investment spending primarily affects long-run aggregate supply by facilitating capital accumulation, which enhances productivity. When businesses invest in new machinery, technology, or infrastructure, they improve their ability to produce goods and services more efficiently. For example, if a factory buys a new automated assembly line, it can produce more products in less time and with fewer workers, leading to higher overall output. This increase in production capacity allows the economy to grow and meet the demands of consumers more effectively. Therefore, investment is crucial because it builds the tools and resources that help workers be more productive over the long term.