In animals the word anatomy is conventionally used for the study of 

Options

A. morphology of external organs
B. morphology of internal organs
C. structure and functional aspects of internal organs
D. all the three

Answer

### Step-by-Step Solution

1. **Understanding Anatomy**: The term "anatomy" refers to the study of the structure of living organisms. It encompasses both the external and internal structures of animals.

2. **Options Analysis**:
- **Option 1**: Morphology of external organs - This refers to the study of the shape and structure of the outer parts of an animal.
- **Option 2**: Morphology of internal organs - This refers to the study of the shape and structure of the internal parts of an animal.
- **Option 3**: Structure and functional aspects of internal organs - This includes not only the structure of internal organs but also how they function.
- **Option 4**: All three - This option suggests that all the previous options are correct.

3. **Evaluating the Options**:
- Since anatomy includes the study of both external and internal structures, as well as their functions, all three options are indeed correct.
- Therefore, the most comprehensive answer is option 4, which states that all three aspects are included in the study of anatomy.

4. **Conclusion**: The correct answer is **all three** (option 4), as anatomy covers the morphology of both external and internal organs, as well as their functional aspects.