Please explain the reason why for each case

Suppose two samples of the same size, n, are taken from a population. Let us call them samples A and B. Case 1: If is known, then the confidence interval for the mean using samples A and B would have: O the same center. O the same width. O the same center and width. O None of the above. Case 2: If is unknown, then the confidence interval for the mean using samples A and B would have: O the same center. O the same width. O the same center and width. O None of the above. Case 3: The confidence interval for the proportion using samples A and B would have: O the same center. O the same width. O the same center and width. O None of the above.