14. In a laboratory study, Dr. Pava gives his test rats daily injections of leptin for a month. Assuming that these test rats are genetically normal, what should Dr. Pava observe over time? A) the rats will have an increased appetite and gain weight B) the rats will have a decreased appetite and lose weight C) the rats will show increased levels of aggression and attack behavior D) the rats will show decreased levels of aggression and attack behavior E) the leptin will not affect the rats in any way