Phylogeny is

Options

A. Castles of flies
B. Development of an organ
C. Developmental history of race.
D. Evolutionary history

Answer

### Step-by-Step Solution:

1. **Understanding Phylogeny**: Phylogeny refers to the evolutionary history and the relationships among various biological species or groups. It is essentially a representation of how different species are related through common ancestry.

2. **Analyzing the Options**:
- **Option 1: Carcels of the flies** - This does not relate to phylogeny, as it does not describe any evolutionary relationships.
- **Option 2: Development of an organ** - This option is incorrect because phylogeny does not focus on the development of individual organs but rather on the evolutionary relationships of species.
- **Option 3: Development history of race** - This is misleading; phylogeny is not limited to a single race but encompasses the evolutionary history of various species.
- **Option 4: Evolutionary history** - This option accurately describes phylogeny as it pertains to the evolutionary history of species and their relationships.

3. **Conclusion**: Based on the analysis of the options, the correct definition of phylogeny is "evolutionary history." Therefore, the answer to the question is **Option 4: Evolutionary history**.