Which Person Is Most Likely to Be Conducting Personality Research

Which person is most likely to be conducting personality research?

A) Josh, who examines changes in extraversion over students' first year in college
B) Casey, who studies how boxers physiologically react to being punched
C) Evelyn, who observes whether people are more likely to stop to help someone in a crowded vs. non-crowded street
D) Lucy, who observes how aggressive behavior varies among people playing a violent vs. non-violent video game