Pierre is preparing to speak before a group of parents about the benefits of after-school tutoring programs. He will claim such programs improve children's standardized test scores. Which of the following pieces of evidence is most likely to be seen as subjective by Pierre's listeners?

A. examples of people who received after-school tutoring as children and went on to academic and professional success
B. statistics from an independent university study showing that children who received at least 3 hours of after-school tutoring a week achieved standardized test scores 15 percent higher than students who received little or no tutoring
C. a paraphrase of the National Teachers Union's definition of effective after-school tutoring
D. a quote of an after-school tutor saying "I have helped dozens of children pass their proficiency exams"

Answer: D