Which one of the following categories of animals, is correctly described with no single exception in it ?

Options

A. All reptiles possess scales, have a three - chambered heart, and are cold blooded ( poikilothermal )
B. All bony fish have four pair of gells and operculum oneach side .
C. All sponges are marrize and have collared cells.
D. All mammals are viviporous and possess diaphragms for breathing.

Answer

To solve the question "Which one of the following categories of animals is correctly described with no single exception in it?", we will analyze each option provided:

### Step 1: Analyze Option A - Reptiles
- **Description**: All reptiles possess scales, have a three-chambered heart, and are cold-blooded (poikilothermic).
- **Evaluation**: This statement is accurate. All reptiles do indeed have scales, a three-chambered heart, and are cold-blooded. There are no exceptions to this description.

### Step 2: Analyze Option B - Bony Fishes
- **Description**: All bony fishes have four pairs of scales and operculum on each side.
- **Evaluation**: This statement is incorrect. While bony fishes do have scales and an operculum, they do not all have the same number of scales. The number of scales can vary widely among different species.

### Step 3: Analyze Option C - Sponges
- **Description**: All sponges are marine and have collared cells.
- **Evaluation**: This statement is also incorrect. While many sponges are marine, there are freshwater sponges as well. Thus, this description does not hold true for all sponges.

### Step 4: Analyze Option D - Mammals
- **Description**: All mammals are viviparous and possess a diaphragm for breathing.
- **Evaluation**: This statement is incorrect. While most mammals are viviparous, there are exceptions such as the monotremes (e.g., the platypus) which lay eggs. Therefore, this description is not universally applicable to all mammals.

### Conclusion
After analyzing all the options, we find that the only category of animals that is correctly described with no exceptions is **Option A: All reptiles possess scales, have a three-chambered heart, and are cold-blooded**.

### Final Answer
**Option A**

---