Answer:
Option B: Paired t-test, since there is a "with music" and "without music" score for each person.
Explanation:
In this question, we have 50 students where each student performed memory test once listening to the music and once without listening to music.
Now, it's obvious that the same set of people are used twice, i.e. once listening to music and second time without listening to music.
We cannot use pooled t test because we don't know about the standard deviation and it is also not a z test because population standard deviation is unknown.
Thus, this will be a case of paired t test or dependent t test because samples in both tests are dependent or same.
So, from the image i attached, the only option that corresponds with my explanation to use paired t-test is option B