Fact 1: Threatening behavior by predators causes a porcupine to extend its quills. Fact 2: Aggression is active, harmful and offensive, threatens all and benefits none. Given the two facts above, what by predators cause porcupines to extend their quills?
pick from the following. a. hypothyroidism b. killing insects c. kisses d. aggression e. love f. hyperthyroidism g. kinetic energy h. cohabitating
d.