Correct option is C
Explanation-
Species richness refers to:
The total number of different species present in a given area or ecological community.
It is a count — not how many individuals there are, not how dense they are, just how many different species exist.
Incorrect options-
Option a : Abundance of species in an area
Abundance refers to the number of individuals per species, not how many different species there are.
Option b : Number and the abundance of species in an area
This describes biodiversity more broadly (especially species diversity), not just species richness.
Option d : Density of species in an area
Density refers to individuals per unit area, again related to abundance, not richness.
So, the correct answer is option c - Number of species present
