Blueprint of chordata is

Options

A. Hemichordata
B. Cephalochordata
C. Urochordata
D. All of the above

Answer

### Step-by-Step Solution:

1. **Understanding the Term "Blueprint of Chordata":**
- The term "blueprint" in this context refers to a fundamental or characteristic structure that defines a group within the Chordata phylum.

2. **Identifying the Key Feature:**
- The most unusual feature of Chordates is the presence of a notochord. This structure is crucial for the classification of organisms within this phylum.

3. **Defining the Notochord:**
- The notochord is a flexible rod-like structure that extends from the head (cephalo) to the tail (cauda) of the organism. This feature is significant in the development of the central nervous system.

4. **Recognizing Cephalocordata:**
- The group that exemplifies this unusual feature is the Cephalocordata. The name itself indicates that the notochord extends from the head to the tail, which is a defining characteristic of this subphylum.

5. **Differentiating Other Groups:**
- Other groups such as Hemichordata and Urochordata have different characteristics:
- **Hemichordata:** These organisms have a partial notochord and other structures like a proboscis and collar, which makes them only partially chordate.
- **Urochordata:** In this group, the notochord is present only in the larval stage and dissolves in the adult form.

6. **Conclusion:**
- Therefore, the blueprint of Chordata is best represented by the Cephalocordata due to the presence of a complete and persistent notochord from head to tail.

### Final Answer:
The blueprint of Chordata is represented by the Cephalocordata, which possesses a notochord extending from the head to the tail.

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