In Slameka and Graf’s (1978) study, some participants read word pairs, while other participants had to fill in the blank letters of the second word in a pair with a word related to the first word. The latter group performed better on a later memory task, illustrating the:
a) spacing effect.
b) generation effect.
c) cued recall effect.
d) multiple trace hypothesis.

(B) Generation effect    

Explanation:

 The generation effect is one of the phenomenon that is specifically moderated by the experimental designing process and in this the information is recall in a much netter way instead of just simply reading the data or information.

 According to the given question, the latter group is basically performed the memory task and the generation effect is best illustrating the given studying process.

 Therefore, Option (B) is correct answer.

answer; i do believe its (b) 12.5 years of age;

i would say b. research typically uses a variety of sources