An ideal evolutionary classification is not possible because

Options

A. an organism shows both advanced and primitive characters
B. evolution occurs in many directions
C. fossil ancestry is not fully explored
D. all of the above.

Answer

### Step-by-Step Solution:

1. **Understanding the Concept of Evolutionary Classification**:
- Evolutionary classification aims to group organisms based on their evolutionary history and relationships. However, achieving an ideal classification is challenging.

2. **Identifying the Reasons**:
- **Reason 1**: Organisms exhibit both advanced and primitive characters. This means that some organisms may possess traits that are considered more evolved, as well as traits that are more primitive, making it difficult to classify them strictly in one category.
- **Reason 2**: Evolution does not occur in a linear or unidirectional manner. Instead, it can occur in multiple directions, leading to a complex web of relationships among organisms. This complexity complicates the classification process.
- **Reason 3**: Fossil records are not fully explored. Many species and their evolutionary relationships remain unknown due to incomplete fossil records, which limits our understanding of the evolutionary history of organisms.

3. **Evaluating the Options**:
- Option A states that organisms show both advanced and primitive characters, which is true.
- Option B states that evolution occurs in many directions, which is also true.
- Option C states that fossil ancestry is not fully explored, which is again true.
- Therefore, since all the statements are correct, the answer is Option D: all of the above.

### Final Answer:
An ideal evolutionary classification is not possible because:
- A) Organisms show both advanced and primitive characters.
- B) Evolution occurs in many directions.
- C) Fossil ancestry is not fully explored.
- D) All of the above (correct answer).