Match the column I (ecologist) with column II (concept).

	Column I		Column II
(a)	Robert May	i.	Relationship between biodiversity and productivity
(b)	Alexander Von Humboldt	ii.	Species-area relationship
(c)	David Tilman	iii.	Global species estimation
(d)	Paul Ehrlich	iv.	Rivet popper hypothesis

Select the correct option

	(a)	(b)	(c)	(d)
1.	i	ii	iii	iv
2.	ii	i	iv	iii
3.	i	ii	iv	iii
4.	iii	ii	i	iv

Robert May estimated that the global species diversity of earth is about 7 million.

A. V. Humboldt observed that within a region, species richness increased with increasing explored area but only up to a limit.

David Tilman concluded that plots with more species show less year to year variation in total biomass and increased diversity contributed to higher productivity.

Paul Ehrlich's Rivet Popper Hypothesis explains the importance of key species.