Read the following statement and select the correct option :
(a) In lancelets notochord extends from head to tail region and is througout their life .
(b) In tunicates ,notochord is present only in the larval tail .

Options

A. (b) is correct but (a) is false
B. (a) is correct but (b) is false
C. both (a) and (b) are true
D. both (a) and (b) are false

Answer

To solve the question, we need to analyze the statements about lancelets and tunicates regarding the presence and persistence of the notochord.

### Step-by-Step Solution:

1. **Understanding Notochord**:
- The notochord is a flexible, rod-like structure found in the dorsal part of the body in chordates. It provides support and is a characteristic feature of the phylum Chordata.

2. **Analyzing Statement (a)**:
- The statement claims that in lancelets (which belong to the subphylum Cephalochordata), the notochord extends from the head to the tail region and persists throughout their life.
- This statement is **true**. In lancelets, the notochord is indeed present from the head to the tail and remains throughout their lifespan.

3. **Analyzing Statement (b)**:
- The statement claims that in tunicates (which belong to the subphylum Urochordata), the notochord is present only in the larval tail.
- This statement is also **true**. In tunicates, the notochord is only present during the larval stage, specifically in the tail region, and is not maintained in the adult form.

4. **Conclusion**:
- Both statements (a) and (b) are correct. Therefore, the correct option is that both statements are true.

### Final Answer:
Both statements (a) and (b) are true.