You are using Firefox as your default browser and you want to customize it to better suit your browsing habits. What extensions specific to Firefox can
you use to accomplish this?

4. what is the reason for including the following code snippet in the header file animal.h? #ifndef animal_h #define animal_h class animal { public: animal(); animal(double new_area_hunt); void birth(); void hunt(double new_area_hunt); void death(); double get_area_hunt() const; private: double area_hunt; }; #endif