One of the Most Striking Aspects of the "Pygmalion in the Classroom

One of the most striking aspects of the "Pygmalion in the Classroom" study by Rosenthal and Jacobson is that

A) once teachers learned about it, they were able to modify their teaching to improve the performance of all of their students.
B) most researchers attempting to replicate the study have found either much smaller effects or no effects at all.
C) it emphasizes the fact that teachers are the primary influence determining whether a child will perform well in school.
D) it indicates that the amount of studying a child does is less important than teacher expectations.