Final answer:
Common stock A is riskier than common stock B based on its higher standard deviation and beta.
Step-by-step explanation:
Common stock A has a higher standard deviation of future returns (25%) compared to common stock B (15%). This means that stock A has a higher level of volatility or risk, as the returns can vary more widely. Additionally, stock A has a higher beta (1.25) compared to stock B (1.50).
Beta measures the sensitivity of a stock's returns to the overall market returns. A higher beta indicates a higher level of systematic risk. Therefore, based on the higher standard deviation and beta, stock A is considered riskier than stock B.