Which of the Following Statements Is True Concerning Clusters

Which of the following statements is True concerning clusters?

A) The desire to build or upgrade a core competency is one reason why entrepreneurial and other fast-growing firms often tend to locate close to their competitors.
B) Clusters are geographic concentrations of interconnected companies and industries.
C) An example of a cluster in the United States is California's Silicon Valley.
D) According to Porter, clusters provide access to employees, suppliers, specialized information, and complementary products.
E) all of the above