Which of the following methods are used to carry out controlled breeding experiments ?

Options

A. Cross - breeding
B. Artificial insemination
C. Interspecific hybridization
D. Out - crossing

Answer

To solve the question regarding which methods are used to carry out controlled breeding experiments, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Controlled Breeding**: Controlled breeding experiments are designed to produce specific traits in offspring by carefully selecting the parents. This involves methods that allow for precise control over mating.

2. **Evaluating the Options**:
- **Option 1: Crossbreeding**: This method involves breeding individuals from different breeds or varieties to produce hybrids. While it can enhance certain traits, it is not a controlled breeding method as it does not guarantee specific outcomes.
- **Option 2: Artificial Insemination**: This is a method where sperm is collected from a male and introduced into the reproductive tract of a female by artificial means. This method allows for precise control over which male contributes to the offspring, making it a valid method for controlled breeding experiments.
- **Option 3: Interspecific Hybridization**: This involves breeding between two different species. While it can produce hybrids, it is not a controlled breeding method in the traditional sense as it often leads to unpredictable results and is not focused on specific traits.
- **Option 4: Outcrossing**: This method involves breeding individuals from different genetic backgrounds within the same species. While it can increase genetic diversity, it is not a controlled breeding method aimed at producing specific traits.

3. **Conclusion**: Based on the evaluation, the only method that is used for controlled breeding experiments is **Artificial Insemination** (Option 2).

### Final Answer:
The correct answer is **Option 2: Artificial Insemination**.