Which of the Following Findings Comes from an Experimental Manipulation

Which of the following findings comes from an experimental manipulation detailed in the text?

A) Boys who used gender labels are more likely than other boys to play with trucks rather than dolls
B) Children spend more time playing with objects they had been told were appropriate to their gender
C) Boys' gender knowledge predicts the extent to which they preferred sex-typed toys and activities
D) Boys' gender knowledge predicts their avoidance of toys and activities associated with girls
E) Girls' gender knowledge is much less predictive of their preferred and avoided toys and activities than it is for boys