Researchers have difficulty ascertaining the relationship between testosterone and human aggression because a. testosterone levels fluctuate dramatically in response to environmental stimuli. b. neurotransmitters complicate matters by also affecting human behavior. c. only males produce testosterone, and it cannot explain female aggression. d. both a and b are correct.

D, both a and b are correct. Measuring the relationship between testosterone and aggression is a complicated task since testosterone levels can vary significantly on outside stimuli on the individual and on the health of that individual. Likewise there are numerous other factors involved in human aggression and various other hormones and neurochemicals that influence aggression. This results in a complex and dynamic system that is difficult to study.

11. gene12. allele13. crossing over14. linked15. gene16. x17. males, femalesapologies if numbers are out of order.