Which of the following tests employs matched-pairs sampling?

A) The Mann-Whitney test.
B) The Wilcoxon rank-sum test.
C) The Wilcoxon signed-rank sum test.
D) None of these choices.

The confidence interval estimate of the expected value of y will be wider than the prediction interval for the same given value of x and confidence level. This is because there is more error in estimating a mean value as opposed to predicting an individual value.