Which one of the following groups of animals is correctly matched with its one characteristic feature without even a single exception
(a) Mammalia : Give birth to young ones .
(b) Reptilia : Possess three - chambered heart with one incompletely divided ventricle
(c) Chordata: Possess a mouth provided with an upper and a lower jaw
(d) Chondrichthyes : Possess cartilaginous endoskeleton

Options

A. Mammalia : Give birth to young ones .
B. Reptilia : Possess three - chambered heart with one incompletely divided ventricle
C. Chordata: Possess a mouth provided with an upper and a lower jaw
D. Chondrichthyes : Possess cartilaginous endoskeleton

Answer

To solve the question, we need to analyze each option and determine whether the characteristic feature mentioned is true for all members of the group without any exceptions.

### Step-by-step Solution:

1. **Option (a): Mammalia - Give birth to young ones.**
- Most mammals are viviparous, meaning they give birth to live young. However, there are exceptions, such as the monotreme known as the platypus, which lays eggs.
- **Conclusion:** This option has exceptions.

2. **Option (b): Reptilia - Possess three-chambered heart with one incompletely divided ventricle.**
- Most reptiles do have a three-chambered heart. However, crocodiles (which are reptiles) have a four-chambered heart.
- **Conclusion:** This option also has exceptions.

3. **Option (c): Chordata - Possess a mouth provided with an upper and a lower jaw.**
- While most chordates do have a jaw, some, like certain species of jawless fish (e.g., lampreys and hagfish), do not possess a jaw.
- **Conclusion:** This option has exceptions as well.

4. **Option (d): Chondrichthyes - Possess cartilaginous endoskeleton.**
- All members of the class Chondrichthyes, which includes sharks and rays, have a cartilaginous skeleton. There are no known exceptions to this characteristic.
- **Conclusion:** This option is correct without exceptions.

### Final Answer:
The correct option is **(d) Chondrichthyes: Possess cartilaginous endoskeleton.**

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