Which of the following statements about the constant growth model for stock valuation are correct? I. The assumption of constant dividend growth rate is generally safe for mature companies that have an established history of regular dividend payments. II. The model fails when companies may have lower rate of return compared to the dividend growth rate. III. The model cannot be used when the growth rate of dividends is zero. IV. The expected capital gains yield changes over time. Multiple Choice I and III I and II II and IV III and IV II and