Which of the following can produce fertile hybrids in captivity?

Options

A. Panthera leo and Panthera tigris
B. Mallard and the Pintail Duck
C. Polar bear and Alaskan brown bear
D. All of these

Answer

To determine which of the given pairs can produce fertile hybrids in captivity, we will analyze each pair individually based on their ability to produce viable and fertile offspring.

### Step-by-Step Solution:

1. **Identify the Pairs**: The question presents four pairs of animals. We need to analyze each pair to see if they can produce fertile hybrids.

2. **Analyze Panthera leo (Lion) and Panthera tigris (Tiger)**:
- These two species can interbreed to produce ligers (lion-tiger hybrids).
- Ligers are known to be large and have high viability.
- However, it is important to note that ligers are typically sterile, meaning they cannot reproduce.

3. **Analyze Mallard Duck and Pink-tailed Duck**:
- These two species can interbreed and produce hybrids.
- The hybrids may have reduced flight capabilities, but their offspring are generally fertile.
- This means that while the hybrids themselves may not be able to fly, they can reproduce.

4. **Analyze Polar Bear and Alaskan Brown Bear**:
- These bears can also interbreed to produce hybrids known as "pizzly" or "grolar" bears.
- The hybrids are viable and fertile, meaning they can reproduce successfully.

5. **Conclusion**:
- Upon analyzing all pairs, we find that while the lion-tiger hybrids (ligers) are typically sterile, the hybrids produced by the other pairs (Mallard-Pink-tailed Duck and Polar Bear-Alaskan Brown Bear) are fertile.
- Therefore, the correct answer is that the Mallard and Pink-tailed Duck, as well as the Polar Bear and Alaskan Brown Bear, can produce fertile hybrids in captivity.

### Final Answer:
The pairs that can produce fertile hybrids in captivity are:
- Mallard and Pink-tailed Duck
- Polar Bear and Alaskan Brown Bear