Hybrid vigour is mostly due to

Options

A. Heterozygosity
B. Superiority of all the genes
C. Homozygosity of pure characters
D. Mixing up of cytoplasm of the male with that of female exclusively.

Answer

**Step-by-Step Solution:**

1. **Understanding Hybrid Vigor**: Hybrid vigor, also known as heterosis, refers to the phenomenon where hybrid offspring exhibit superior qualities compared to their parents. This can include increased growth rate, higher yield, and greater resistance to diseases.

2. **Identifying the Cause of Hybrid Vigor**: The primary reason for hybrid vigor is heterozygosity. Heterozygosity occurs when an organism has two different alleles for a particular gene, leading to a more diverse genetic makeup.

3. **Evaluating the Options**:
- **Option A: Heterozygosity** - This is the correct answer. It indicates that the genetic diversity from combining different parental traits contributes to the vigor of the hybrid.
- **Option B: Superiority of all genes** - This is incorrect because hybrid vigor is not about all genes being superior, but rather about the dominance of certain alleles.
- **Option C: Homozygosity of pure character** - This is also incorrect. Homozygosity refers to having identical alleles, which does not contribute to hybrid vigor.
- **Option D: Mixing of cytoplasm of the male with the female exclusively** - This option is misleading. While cytoplasmic mixing can occur in hybrids, it is not the primary cause of hybrid vigor.

4. **Conclusion**: Therefore, the correct answer to the question "Hybrid vigor is mostly due to" is **A. Heterozygosity**.

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