Nhận biết (M1)

To study how sleep duration affects memory, researchers had four groups of participants learn a list of word pairs and then tested their recall after different amounts of sleep. The table shows the average percentage of word pairs each group correctly recalled.

Sleep duration (hours) Word pairs recalled (%)

2 41

4 55

6 72

8 78

The researchers concluded that recall improved as sleep increased but that the benefit diminished at longer durations.

Which choice best describes data from the table that support this conclusion?

• A.

  Recall rose with each increase in sleep, yet the gain from 6 to 8 hours (6 points) was smaller than the gain from 4 to 6 hours (17 points).

• B.

  Participants who slept 8 hours recalled a higher percentage of word pairs than any other group.

• C.

  Participants who slept only 2 hours recalled fewer than half of the word pairs.

• D.

  Recall was nearly identical for the participants who slept 6 hours and those who slept 8 hours.