Tissues of oleander plants contain chemicals that
are poisonous to many mammals. The production
of these poisonous chemicals most likely benefits
oleanders by preventing leaf loss caused by
(1) lack of rain (3) mineral absorption
(2) scavengers (4) herbivores
The answer would be 4) Herbivores which are animals that eat only vegetation like goats, deer, and rabbits. Some mammals are actually able to eat oleander due to built up immunities to the chemicals, but most avoid the plant.
