Species is

Options

A. Group of individuals occurring in a geographical area
B. Population of one type
C. Population or populations of individuals with similar genotypic and phenotypic traits
D. Population or populations of interbreeding individuals

Answer

### Step-by-Step Text Solution:

1. **Understanding the Definition of Species**:
- A species is typically defined as a group of organisms that can interbreed and produce fertile offspring. This concept emphasizes the reproductive isolation of one species from another.

2. **Ernest Mayr's Definition**:
- The most recognized definition of a species comes from biologist Ernest Mayr, who stated that a species is a group of interbreeding individuals that are reproductively isolated from other such groups. This means that members of a species can mate with each other but not with members of other species.

3. **Analyzing the Options**:
- **Option A**: "A group of individuals occurring in a geographical area."
- This is incorrect because it does not specify interbreeding or reproductive isolation.
- **Option B**: "The population of one type."
- This is too vague and does not capture the essence of species as defined by reproductive isolation.
- **Option C**: "The population and populations of individuals with similar genotypic and phenotypic traits."
- While this option mentions traits, it fails to address the critical aspect of interbreeding and reproductive isolation.
- **Option D**: "Population and populations of interbreeding individuals."
- This aligns perfectly with Mayr's definition, emphasizing interbreeding and reproductive isolation.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Option D**, which accurately reflects the definition of a species as per Ernest Mayr.