Houston, Texas, is a major hub of the American energy industry. In addition to global oil and gas firms Shell and ConocoPhillips, there are many, many supporting industries like Enertia Software, which designs software for oil and gas companies, Rampart Products, which manufactures component parts for oil and gas extraction, and Riverbend Energy Group, an energy investment firm. This is a good example of which of the following factors driving spatial agglomeration? Question 13 options: the creation of new business activity tacit knowledge spillovers matching labor to employment access to specialized suppliers