The procedure adopted by Mendel which was different from his predecessors in:

Options

A. Keeping breeding records
B. Employing many triats at one time
C. Differentiating inherited traits
D. Quantitative analysis of data.

Answer

### Step-by-Step Solution:

1. **Understanding Mendel's Approach**: Mendel's experiments were groundbreaking in the field of genetics. He used the pea plant for his studies due to its ease of cultivation and the ability to self-pollinate, which allowed him to control breeding.

2. **Selection of Traits**: Mendel selected seven distinct traits in pea plants, each with two contrasting forms (e.g., tall vs. short plants). This selection was crucial for observing inheritance patterns.

3. **Quantitative Analysis**: Unlike his predecessors, Mendel employed a methodical approach to analyze the data he collected. He meticulously recorded the ratios of phenotypes and genotypes from his experiments, which allowed him to derive the laws of inheritance.

4. **Comparison with Predecessors**: Previous geneticists did not focus on quantitative data. They often relied on qualitative observations without systematic data analysis. Mendel’s emphasis on numbers and ratios set his work apart.

5. **Conclusion**: The most significant difference in Mendel's procedure compared to his predecessors was his use of quantitative analysis of data. This approach enabled him to formulate the foundational principles of genetics.

### Final Answer:
The procedure adopted by Mendel which was different from his predecessors is the **quantitative analysis of data**.

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