Elliott,a 43-Year-Old Engineer,has Volunteered to Teach a Group of Middle-School

Elliott,a 43-year-old engineer,has volunteered to teach a group of middle-school students some hands-on engineering basics,hoping to get them oriented toward a math-science career path.Performance of the 1/3 of the group,who are girls,is lower than average.What is one likely cause for this effect?

A) the girls have supported Elliott's belief that girls cannot perform as well as boys in engineering
B) the girls did not engage in self-stereotyping
C) Elliott did not call on the boys more than the girls when he asked questions in the class
D) when one girl did well on a board problem,Elliott did not act surprised
E) the guys were not more highly motivated to please Elliott