Select the correct statement from the following .

Options

A. All vertebrates are chordates .
B. All protochordates are craniates.
C. All echinoderms are freshwater animals.
D. Post - anal tail is always present in chordates.

Answer

To solve the question, we need to evaluate each of the four statements provided and determine which one is correct. Let's analyze them step by step.

### Step 1: Evaluate the first statement
**Statement:** "All the vertebrates are caudates."

- **Analysis:**
- Vertebrates belong to the subphylum Vertebrata, which is part of the phylum Chordata (also known as caudates).
- All vertebrates possess a notochord at some stage of their development, which is a characteristic of caudates.
- Therefore, this statement is **true**.

### Step 2: Evaluate the second statement
**Statement:** "All the protocordates are craniates."

- **Analysis:**
- Protocordates (which include groups like cephalochordates and urochordates) do not possess a true skull (cranium).
- Craniates are defined as vertebrates that have a skull.
- Since protocordates lack a true backbone and skull, this statement is **false**.

### Step 3: Evaluate the third statement
**Statement:** "All the echinoderms are freshwater animals."

- **Analysis:**
- Echinoderms are primarily marine organisms and do not have freshwater or terrestrial forms.
- Therefore, this statement is **false**.

### Step 4: Evaluate the fourth statement
**Statement:** "The post-anal tail is always present in the caudates."

- **Analysis:**
- While most caudates (including vertebrates) have a post-anal tail at some stage of their life cycle, not all caudates retain this feature in adulthood (e.g., some urochordates lose the tail in their adult form).
- Therefore, this statement is **false**.

### Conclusion
After evaluating all four statements, we find that the only correct statement is the first one: "All the vertebrates are caudates."

### Final Answer
The correct statement is **Option 1**: "All the vertebrates are caudates."

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