Options are: 1. hyperthyroidism; 2. aggressive; 3. hormones; 4. humans; 5. bullfrogs; 6. hypothyroidism; 7. similar; 8. some mammals;
Q: Fact 1: Threatening behavior causes a fight-or-flight response in animals. Fact 2: If a pony feels threatened it can respond with aggressive behavior. Given the two facts above, what sort of behavior can cause fight-or-flight responses?
A:
2.