A researcher tells a school principal in a gang neighborhood that she should ignore a juvenile's minor act of vandalism because the act of arresting the child might result in his being identified by the police as a gang member even though he isn't one. This identification of him as a gang member, the researcher says, might contribute to pushing the juvenile from primary (occasional and experimental) deviance into secondary (habitual or career) deviance. This researcher subscribes to the theory called ______.
A. structural-strain theory
B. labeling theory
C. control theory
D. conflict theory
E. opportunity theory