A Researcher Observed Variation in Plasma Testosterone Hormone Levels in Birds

Multiple Choice

A researcher observed variation in plasma testosterone hormone levels in birds that was associated with variation in aggression: birds with higher levels of testosterone were more aggressive. In addition, experimental addition of testosterone increased an individual's level of aggression. Which of the following is correct about this work?

A) It is a proximate explanation of behavior
B) The results contradict Morgan's canon
C) An ethogram of this species should include testosterone level
D) It builds on the work of Ivan Pavlov
E) It exemplifies the comparative method