Biodiversity is determined by :

Options

A. Number of individuals in an area
B. Species richness
C. Evenness
D. Both B and C.

Answer

### Step-by-Step Solution:

1. **Understanding Biodiversity**:
- Biodiversity refers to the variety and variability of living organisms in a particular area. This includes both plants and animals.

2. **Components of Biodiversity**:
- Biodiversity is measured at different levels: genetic, species, and ecosystem levels. Each of these levels contributes to the overall biodiversity of an area.

3. **Key Factors Determining Biodiversity**:
- The two major factors that determine biodiversity are **species richness** and **species evenness**.
- **Species Richness**: This refers to the number of different species present in a particular area. It indicates the variety of species in that region.
- **Species Evenness**: This represents the relative abundance of different species within a community. It measures how evenly the individuals are distributed among the different species.

4. **Evaluating the Options**:
- Given the options:
- A) Number of individuals in an area
- B) Species richness
- C) Evenness
- D) Both B and C
- We can see that options B (species richness) and C (evenness) are both essential components that determine biodiversity.

5. **Conclusion**:
- Therefore, the correct answer to the question "Biodiversity is determined by:" is **option D: both B and C** (species richness and evenness).