Answer: 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.
Step-by-step explanation:
A cluster is the concentration of industries, businesses, or suppliers, that are interrelated in a particular field.
According to Porter, clusters bring about increase the productivity, stimulate new business, drives innovation and they're vital to strategic management.
Of the options given, the answer is "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".