If possible I'd say all of them except the fourth one down (parts of ecosystems are independant) but if not I'd say the most valid one is the second one down (healthy ecosystems help animals)
The correct answer should be an implicit idea found in things such as allegories. It's like watching a fable, it's not really about the animals but rather it has a meaning that is understood by us and that is implicit, not explicitly said. Implicit ideas are common and are used in almost all works of art, from writing to painting to sculpting.
