Read the following statements and select the correct option :
(a) All vertebrates are chordates
(b) All chordates are vertebrates

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 two statements provided:

1. **Statement (a)**: All vertebrates are chordates.
2. **Statement (b)**: All chordates are vertebrates.

### Step-by-Step Solution:

**Step 1: Understand the definitions of chordates and vertebrates.**
- Chordates belong to the phylum Chordata, which is characterized by the presence of a notochord at some stage of their development. This phylum includes a wide variety of animals, including both vertebrates and invertebrates.
- Vertebrates are a subphylum of Chordata known as Vertebrata, which includes animals with a backbone (vertebral column).

**Step 2: Analyze Statement (a).**
- Since all vertebrates possess a notochord at some stage of their development (even if it is replaced by a vertebral column in adults), it is correct to say that all vertebrates are indeed chordates.

**Step 3: Analyze Statement (b).**
- Not all chordates are vertebrates. The phylum Chordata includes subphyla such as Urochordata (tunicates) and Cephalochordata (lancelets), which do not have a backbone. Therefore, this statement is incorrect.

**Step 4: Conclusion.**
- Based on the analysis:
- Statement (a) is true: All vertebrates are chordates.
- Statement (b) is false: Not all chordates are vertebrates.

### Final Answer:
The correct option is:
- Statement (a) is correct, and Statement (b) is incorrect.