The correct answer is: B. economic factors
Economic factors are the factors that affect the overall economy, such as interest rates, inflation, and GDP growth. These factors can have a significant impact on the stock market, as they can affect the demand for stocks and the prices of stocks.
Arbitrage factors are the factors that allow investors to make risk-free profits by taking advantage of price differences in different markets. These factors are typically very small and difficult to exploit, but they can be profitable for experienced investors.
Portfolio factors are the factors that affect the performance of a portfolio of stocks, such as diversification, asset allocation, and rebalancing. These factors can be used to improve the risk-adjusted returns of a portfolio.
Realized theory factors are the factors that are used to explain the realized returns of stocks. These factors include the risk premium, the size premium, and the value premium.
In conclusion, the correct answer is: B. economic factors.