According to species-area relationships, the relation between species richness and area for a wide variety of taxa (angiosperms, birds, bats and freshwater fishes) turns out to be a:

Rectangular hyperbola

The correct answer is Option (3) → Rectangular hyperbola 

Species-Area relationships : During his pioneering and extensive explorations in the wilderness of South American jungles, the great German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit.

In fact, the relation between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turns out to be a rectangular hyperbola. On a logarithmic scale, the relationship is a straight line described by the equation

log S = log C + Z log A

where S= Species richness

A= Area

Z = slope of the line (regression coefficient)