Final answer:
Government policy can affect financial market prices by impacting production costs and the supply curve, as seen with taxes, regulations, and subsidies which increase operational costs for businesses, potentially resulting in higher prices for consumers.
Step-by-step explanation:
Among the options provided, government policy is a significant unknown factor that can affect prices in financial markets. Government policies have a substantial impact on the cost of production and the supply curve through the implementation of taxes, regulations, and subsidies. For example, the tax imposed by the U.S. government on alcoholic beverages, which amounts to about $8 billion per year from producers, is an additional cost businesses must bear. These types of costs lead to a decrease in supply, as a result of higher production costs, thereby affecting prices.
Moreover, compliance with government regulations, such as those to ensure a cleaner environment or safer workplace, also increases costs for firms. This, in turn, can lead to higher prices for consumers. By adjusting these policies, the government can influence overall economic performance, which includes factors such as real GDP growth and the unemployment rate.