Which of the following statements about confidence intervals for proportions are true? I. The confidence interval formula for proportions is valid if np 2 5 and n(1-p) 25. II. Confidence intervals with large sample size always contain the true parameter value, whereas confidence intervals with small sample size may not. III. 99% CI is narrower than 95% CI. A. I and III only B. II only C. I only I, II, and