Match List I with List II

List I		List II
A.	Robert May	I.	Species-Area relationship
B.	Alexander von Humboldt	II.	Long term ecosystem experiment using out door plots
C.	Paul Ehrlich	III.	Global species diversity at about 7 million
D.	David Tilman	IV.	Rivet popper hypothesis

Choose the correct answer from the options given below:

The correct option is A-III, B-I, C-IV, D-II.

Let us match the scientists/ecologists in List I with their respective discoveries, hypotheses, or contributions in List II step-by-step:
1. A. Robert May: Robert May is famous for proposing a scientifically sound global estimate of species diversity. He estimated the total number of global species diversity to be around 7 million (Matches with III. Global species diversity at about 7 million).
2. B. Alexander von Humboldt: The German naturalist and geographer Alexander von Humboldt observed that within a region, species richness increases with increasing explored area, but only up to a limit. This is known as the species-area relationship (Matches with I. Species-Area relationship).
3. C. Paul Ehrlich: Stanford ecologist Paul Ehrlich proposed the "Rivet Popper hypothesis" to explain the significance of species diversity to the ecosystem. In this analogy, ecosystems are compared to airplanes, and species are compared to the rivets holding the airplane together (Matches with IV. Rivet popper hypothesis).
4. D. David Tilman: David Tilman performed long-term ecosystem experiments using outdoor plots. He showed that plots with more species showed less year-to-year variation in total biomass, thus linking species richness to ecosystem stability (Matches with II. Long term ecosystem experiment using out door plots).

Therefore, the correct mapping is:
A ⇒ III
B ⇒ I
C ⇒ IV
D ⇒ II