Animals which possess cleidoic eggs exhibit

Options

A. External fertilization and internal development
B. Internal fertilization and internal development
C. Internal fertilization and external development
D. External fertilization and external development

Answer

### Step-by-Step Solution

1. **Understanding Cleidoic Eggs**: Cleidoic eggs, also known as amniotic eggs, are a type of egg that is enclosed in a protective shell. This adaptation allows the eggs to be laid in a terrestrial environment, providing a safe environment for the developing embryo.

2. **Characteristics of Cleidoic Eggs**: Cleidoic eggs are characterized by their closed structure, which prevents desiccation (drying out) and allows for the exchange of gases. This is crucial for the survival of the embryo in a land environment.

3. **Occurrence in Animals**: Cleidoic eggs are primarily found in amniotes, which include reptiles (like snakes and lizards) and birds (aves). These groups of animals have evolved to reproduce on land, which is why they possess these types of eggs.

4. **Fertilization Process**: In animals that lay cleidoic eggs, fertilization is typically internal. This means that the sperm fertilizes the egg inside the female's body before the egg is laid. This internal fertilization is necessary to ensure the survival of the embryo in a terrestrial environment.

5. **Development Process**: After the eggs are laid, the development of the embryo occurs externally. This means that the embryo develops outside of the mother's body, within the protective shell of the egg. The environment outside the egg provides the necessary conditions for growth until the embryo is ready to hatch.

6. **Conclusion**: Therefore, the correct answer to the question is that animals which possess cleidoic eggs exhibit **internal fertilization and external development**.