In some countries, the buying and selling of animals such as orangutans and leatherback turtles have been banned. These animals need to be protected so that ________

Options

A. Their value can increase
B. Their numbers can increase
C. The zoos can attract more visitors
D. Scientists can have more animals to experiment with

Explanation

To solve the question, "In some countries, the buying and selling of animals such as orangutans and leatherback turtles have been banned. These animals need to be protected so that ________," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Context**: The question mentions that the buying and selling of certain animals, like orangutans and leatherback turtles, has been banned. This indicates a concern for their conservation.

**Hint**: Think about why countries would impose such bans on specific animals.

2. **Identify the Purpose of Protection**: The purpose of protecting these animals is likely to prevent their extinction and ensure their survival in the wild.

**Hint**: Consider what happens to animal populations when they are not protected.

3. **Analyze the Options**: The options provided suggest various outcomes of the ban. We need to determine which outcome aligns with the goal of protecting these animals.

- **Increase in their value**: This does not directly relate to their protection.
- **Increase in their number**: This is a direct goal of conservation efforts.
- **Attracting more visitors**: While this might be a benefit, it is not the primary goal of protection.
- **More animals for scientific experiments**: This is not a reason for their protection.

**Hint**: Focus on the primary goal of conservation efforts related to endangered species.

4. **Choose the Correct Answer**: Based on the analysis, the most logical answer is that these animals need to be protected so that **their number can increase**.

**Hint**: Reflect on the importance of maintaining biodiversity and the role of conservation in achieving this.

### Final Answer:
These animals need to be protected so that **their number can increase**.