[单项选择]It is a big day for the "expert baby.’ A minivan bearing an official University of Washington seal picks up the 14-month-old boy and his mother and takes them to a Seattle day-care center. Once inside, he is placed at the head of a table surrounded by his "students," a bevy of babies his age. Researchers from the university’s psychology department observe and take notes. The miniprofessor begins his lesson: Whaaack! He smacks the top of a special camping cup with his palm, and it collapses. His pupils look at one another, wide-eyed. Then he deftly pulls apart a puzzle and puts it back together. As a finale, he hits a hidden button on a box, which produces a buzzing sound. A delighted squeal rises from the audience. Wunderkind is then whisked away. Two days later, a researcher visits the houses of each of the young pupils, unpacking a black bag to reveal the little-professor’s toys. The infants grin in recognition and repeat the tricks they observed. Like the expert baby befor
A. the toys the miniprofessor used
B. the babies taking part in the research
C. the researchers conducting the study
D. the teachers at the day-care center