Which of the following are reasons for Mendel's success ?
(i) Usage of pure lines or pure breeding varieties
(ii) Consideration of one character at a time
(iii) Maintenance of statistical records of experiments
(iv) Knowledge of linkage and incomplete dominance

Options

A. (i) and (ii) only
B. (i),(ii) and (iii)
C. (i) and (iv) only
D. (ii),(iii) and (iv)

Explanation

To determine the reasons for Mendel's success in his experiments on inheritance, we will analyze each of the provided statements one by one.

### Step-by-Step Solution:

1. **Usage of Pure Lines or Pure Breeding Varieties**:
- Mendel used pure breeding varieties for his experiments. This means that he started with plants that were genetically uniform, which allowed him to observe the inheritance patterns clearly without the interference of other traits.
- **Conclusion**: This statement is correct.

2. **Consideration of One Character at a Time**:
- Mendel focused on one trait at a time (for example, flower color or seed shape) in his experiments. This simplification allowed him to track the inheritance of that single trait without the complications that arise from multiple traits interacting.
- **Conclusion**: This statement is correct.

3. **Maintenance of Statistical Records of Experiments**:
- Mendel meticulously recorded the results of his experiments, applying statistical methods to analyze the data. This helped him to draw reliable conclusions about inheritance patterns.
- **Conclusion**: This statement is correct.

4. **Knowledge of Linkage and Incomplete Dominance**:
- Mendel did not have knowledge of genetic linkage or incomplete dominance. His work was based on the principles of dominance, segregation, and independent assortment. He did not account for the complexities of linkage or the phenomenon of incomplete dominance in his experiments.
- **Conclusion**: This statement is incorrect.

### Final Answer:
The correct statements regarding Mendel's success are:
- (i) Usage of pure lines or pure breeding varieties: **Correct**
- (ii) Consideration of one character at a time: **Correct**
- (iii) Maintenance of statistical records of experiments: **Correct**
- (iv) Knowledge of linkage and incomplete dominance: **Incorrect**

Thus, the reasons for Mendel's success are (i), (ii), and (iii).