Crocodile and penguin are similar to whale and dog fish in which one of the following features?

Options

A. Posses a solid single stranded central nervous system
B. Lay eggs and guard them till they hatch
C. Posses bony skeleton
D. Have gill slits at some stage

Explanation

To solve the question about the similarities between crocodiles, penguins, whales, and dogfish, we can follow these steps:

### Step 1: Identify the Organisms
- **Crocodile**: A reptile that lays eggs and is part of the class Reptilia.
- **Penguin**: A bird that also lays eggs and belongs to the class Aves.
- **Whale**: A mammal that gives live birth but has ancestors that laid eggs, belonging to the class Mammalia.
- **Dogfish**: A type of fish that lays eggs and belongs to the class Chondrichthyes.

### Step 2: Analyze the Options
- **Option A**: Possesses a solid single standard central nervous system.
- This feature is common to all vertebrates but does not specifically relate to the similarities among the given animals.

- **Option B**: Lays eggs and guards them till they hatch.
- While crocodiles and penguins do guard their eggs, whales do not lay eggs as they give live birth, making this option not applicable to all.

- **Option C**: Possess bony skeleton.
- Crocodiles and penguins have bony skeletons, but dogfish have cartilaginous skeletons, making this option incorrect.

- **Option D**: Having gill slit at some stages.
- All these animals (crocodiles, penguins, whales, and dogfish) have gill slits at some stage of their development, which is a characteristic feature of chordates.

### Step 3: Conclusion
Based on the analysis, the correct answer is **Option D: Having gill slit at some stages**. This feature is a common characteristic of all the mentioned animals during their developmental stages.

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