Which of the Following Poses a Serious Problem When Using

Multiple Choice

Which of the following poses a serious problem when using a t test for dependent means, one-tailed?

A) The population of difference scores is even moderately different from normal.
B) The sample has less than 40 participants.
C) There is a ceiling effect in the test, which is likely to make the population of difference scores highly skewed.
D) Pretest and posttest scores are highly correlated with each other.