A researcher wishes to determine whether listening to music affects students' performance on memory test. He randomly selects 50 students and has each student perform a memory test once while listening to music and once without listening to music. He obtains the mean and standard deviation of the 50 "with music" scores and obtains the mean and standard deviation of the 50 "without music scores". Indicate the correct test procedure and reasoning.

Choose the best answer below:

A. Paired t-test, since there is a "with music" and "without music" score for each person.

Two-sample t-test, since the researcher has two samples.

B. z-test for each sample, since the researcher has the sample standard deviation.

C. Not enough information given to determine correct type of test.

D. Pooled t-test, since the standard deviation is likely to be the same in both populations.