Back cross is

Options

A. `F_(1)xx` Recessive parent
B. `F_(1)xx` Dominant parent
C. `F_(1)xx` Any parent.
D. All of above

Answer

### Step-by-Step Solution:

1. **Understanding Back Cross**:
- A back cross is a specific type of genetic cross. It involves crossing an F1 individual (the first filial generation) with one of its parent organisms.

2. **Identifying the F1 Individual**:
- The F1 individual is the offspring resulting from the initial cross between two different parental lines. This individual typically exhibits a combination of traits from both parents.

3. **Crossing with Parent**:
- In a back cross, the F1 individual is crossed with one of the original parent organisms from which it was derived. This can be either the dominant parent or the recessive parent.

4. **Results of Back Cross**:
- When the F1 individual is back crossed with the dominant parent, all offspring will display the dominant phenotype, and no recessive individuals will be produced.
- Conversely, when the F1 individual is back crossed with the recessive parent, the resulting offspring will exhibit both dominant and recessive phenotypes.

5. **Conclusion**:
- Therefore, the back cross can yield different results depending on which parent the F1 individual is crossed with. The correct answer to the question is that back cross can involve crossing with either parent, leading to the conclusion that the answer is "all of the above".