Which one is correct

Options

A. Flatworms are eucoelomates
B. Fishes are radially symmetrical
C. Birds aer poikilothermic
D. Earthworm is metamerically segmented.

Answer

To determine which statement is correct among the given options, we will analyze each one step by step.

### Step 1: Analyze the first option - "Flatworms are eucelomates."
- Flatworms, which belong to the phylum Platyhelminthes, are known to be acoelomate, meaning they do not have a true coelom. Instead, they have a solid body without a body cavity. Therefore, this statement is incorrect.

### Step 2: Analyze the second option - "Fishes are radially symmetrical."
- Radial symmetry means that the organism can be divided into similar halves by multiple planes passing through the central axis. Fishes, however, exhibit bilateral symmetry, where they can be divided into two equal halves only along one plane. Thus, this statement is also incorrect.

### Step 3: Analyze the third option - "Birds are poikilothermic."
- Poikilothermic animals are those whose body temperature varies with the environment, commonly referred to as cold-blooded animals. Birds, on the other hand, are warm-blooded (homeothermic) as they maintain a constant body temperature regardless of the environment. Therefore, this statement is incorrect as well.

### Step 4: Analyze the fourth option - "Earthworm is metamerically segmented."
- Earthworms belong to the phylum Annelida, which is characterized by metameric segmentation. This means their bodies are divided into repeated segments. This statement is correct.

### Conclusion:
The correct statement among the options provided is: **"Earthworm is metamerically segmented."**

---