A—
This sentence pretty much sums up what the writer of the passage wants to talk about. The other ones do not fit with the sentence “water is one factor that is necessary for growth” and do not fit the idea of the passage, which is what factors affect plant growth.
Vestigial usually refers to traits which over evolution have lost their main function and are less useful than they once were.
In number one Hunter means that he thinks the teeth were from the ancestor whale shark but are now useless or nearly useless to the current whale shark.
Different- mount olympus is in nyc at the top of the empire state building (an actual place in the human world) & above the world (very top floor that does not really exists to humans); underworld is a place that non humans never see/know of & it's under the world
It is logical to me to assume that it is all of the above.