Dr. Prentice, principal of an elementary school, instructs her teachers to employ a new aggression-reduction program with the second graders and to keep using it on that group of students for the next three years. She finds that, relative to the start of the program, aggression in that group of students is down 35%. This example illustrates the possibility of ________________ as a plausible rival hypothesis. Group of answer choices history maturation attrition selection

As per the question, the given description exemplify the possibility of 'maturation' as a credible rival hypothesis because it may argue the possibility of aggression-reduction program as an effective source to lowering the aggression among the students to 35%. The program claims that maturation of the program developed the students into a more peaceful and friendly individual in relation to the aggression they possessed in the first year. Therefore, the prospect of maturation could be considered a reliable rival hypothesis as it could question the efficacy of the program in lowering the aggression at the end of the program. Thus, option B is the correct answer.