Answer: You have a matched pairs of scores., The sampling distribution of d is normal.

The correct conditions for a paired t-test are B and C. Option B ('You have a matched pairs of scores') is essential as paired t-tests require paired observations (e.g., measurements from the same subject before and after treatment). Option C ('The sampling distribution of d is normal') is correct because 'd' represents the differences between paired scores, and normality of these differences is a key assumption. Option A is incorrect because it states 'All scores are independent from each other,' but in paired t-tests, scores within pairs are dependent; the correct condition is that each pair is independent of other pairs. Option D ('The sampling distribution of x1- x2 is normal') is redundant and misleading; 'x1-x2' refers to the same differences as 'd' in option C, but D is often associated with unpaired t-tests, making it less precise. The community discussion strongly supports BC, with high upvotes for comments citing official Microsoft documentation and clarifying that A and D are not accurate for paired t-tests.

Author: LeetQuiz Editorial Team