The answer in this scenario is regulation (Answer B).
Education results in a more skilled and productive work force, technological advancement improves efficiency and therefore productivity, and trade promotes increases in productivity.
Regulation, while necessary in many industries, is a form of restriction. This often means it drives up the cost in providing goods and services which dampens productivity. It's important to note that regulation is a very important tool to protect certain aspects or parties within an industry. For example, regulation is often in place to limit the maximum price that consumers (like you) can be charged for essential services like energy, water and sewerage.
