Research has documented that it is common in Silicon Valley both for companies to expand rapidly and for workers to switch employers. To what type of external economy does this finding refer and why? Source: Annalee Saxenian. Regional Advantage. Cambridge: Harvard University Press, 1994. A fascinating comparison of two high-technology industrial districts, California's Silicon Valley and Boston's Route 128. The finding that companies often expand rapidly and workers often switch employers in Silicon Valley refers to O A. way in which a geographically concentrated industry helps foster knowledge spillovers-the informal exchange of information and O B. C. 0 D. ideas that takes place at a personal level and seems most effective when employees of different companies in a fairly small area mix socially and talk freely about technical issues. the ability of localized industrial clusters to support specialized suppliers the dense network of suppliers of specialized equipment or support that provides the high-tech firms in Silicon Valley with flexibility and cost savings in sourcing. the way in which localized industrial clusters allow for labor market pooling-the increased likelihood that firms will be able to hire as many workers as they want to take advantage of business opportunities, and that workers will have a lower risk of unemployment. the way in which localized industrial clusters are affected by the external demand for high-tech innovations-the evergrowing dependence on technological innovation to improve products and services