The only type of pollination which during pollination brings genetically different types of pollen grains to the stigma, is:
(a) Xenogamy
(b) Geitonogamy
(c) Chasmogamy
(d) Autogamy

Options

A. Xenogamy
B. Geitonogamy
C. Chasmogamy
D. Autogamy.

Answer

To solve the question regarding the type of pollination that brings genetically different types of pollen grains to the stigma, we can analyze each option provided:

1. **Understanding the Options:**
- **(a) Xenogamy:** This is a type of cross-pollination where pollen is transferred from the anther of one flower to the stigma of another flower, often of a different plant. This ensures genetic diversity since the pollen grains come from different genetic sources.
- **(b) Geitonogamy:** This is a form of self-pollination where pollen from one flower is transferred to another flower on the same plant. Since both flowers are genetically identical, this does not bring genetically different pollen grains to the stigma.
- **(c) Chasmogamy:** This refers to the opening of flowers that allows for pollination to occur. While it can involve cross-pollination, it can also involve self-pollination, meaning it does not guarantee genetically different pollen grains.
- **(d) Autogamy:** This is self-pollination where pollen from the same flower fertilizes its own ovules. This does not bring in genetically different pollen grains.

2. **Analyzing the Correct Answer:**
- Given the definitions, **Xenogamy** is the only option that explicitly involves the transfer of genetically different pollen grains from different plants to the stigma. This leads to genetic variation in the offspring.

3. **Conclusion:**
- Therefore, the correct answer to the question is **(a) Xenogamy**.