An experimenter tests older and younger adults' memory for pictures and words. First (s)he presents the participants with a study list consisting of both pictures and words. Immediately after the list is presented, participants are asked to recall in any order as many of the list items as possible. Which of the following describes an interaction?

a) Older adult's memory for pictures is much greater than for words. Younger adults show the picture advantage but to a lesser degree.

b) Older adults overall memory performance is worse than younger adults, but both groups show an equivalent advantage for pictures over words.

c) Older adult's memory performance is more variable than younger adults.

d) Younger adults' memory is more capricious than older adults.