A sample of first-year psychology students participates in a memory test conducted by a cognitive psychologist. A list  of 20 words is given  to the students in the order listed below, and they are requested to listen to the words.

wolf cat house dolphin elephant apartment library sardine carrot cherry dog whale shark gorilla barracuda apple church hospital orange school

The psychologist tests the participants individually.  She first reads the list of words to each participant, and after reading the list, the psychologist instructs them to recall as many of the words as possible in the order they were presented.  The following are the recall data produced by four different students; the words are recalled in the order indicated: 

Student A:      wolf cat elephant sardine apple house dolphin 

Student B:      library sardine apple carrot cherry dog whale gorilla 

Student C:      orange school church apple hospital cat house wolf 

Student D:      school church hospital house orange apple cherry barracuda shark dolphin gorilla dog cat wolf elephant 

Which of the students’ recall data most clearly displays a primacy effect?