What policy involves adjusting interest rates to control the money supply in the economy?

Monetary policy is the correct answer because it specifically refers to the actions taken by a country's central bank to manage the money supply and influence interest rates in order to achieve economic goals, such as controlling inflation, maintaining employment levels, and fostering economic growth. By adjusting interest rates, a central bank can either encourage or discourage borrowing and spending. For instance, lowering interest rates generally makes loans cheaper, which can stimulate economic activity by encouraging consumers and businesses to borrow and spend more, whereas raising interest rates can help to cool off an overheating economy by making borrowing more expensive.

In contrast, fiscal policy involves government spending and tax policies to influence the economy, so it does not relate to interest rates directly. Social policy and health policy relate to governmental programs and regulations aimed at improving social welfare and public health, respectively, and are not tied to monetary control mechanisms such as interest rate adjustments. Understanding the distinction between these policies is crucial for grasping how different branches of government and financial institutions operate within the economy.