Which of the following options is correct ?

Options

A. Transfer of pollen grains from the anther to the stigma of the same flower - Autogamy
B. Transfer to pollen grains from the anther of one flower to the stigma of another flower of same plant-Geitonogamy
C. Trasfer of pollen grains from the anther to the stigma of a genetically different plant of same species-Xenogamy
D. All of these

Answer

To determine which of the options is correct regarding the types of pollination in flowering plants, we can analyze each option step by step:

### Step-by-Step Solution:

1. **Understanding Autogamy**:
- Autogamy is defined as the transfer of pollen grains from the anther to the stigma of the same flower.
- This means that self-pollination occurs within the same flower.
- **Examples**: Common examples of autogamous plants include wheat, barley, oats, and rice.

2. **Understanding Zetonogamy**:
- Zetonogamy refers to the transfer of pollen grains from the anther of one flower to the stigma of another flower on the same plant.
- This type of pollination is also known as self-pollination but occurs between different flowers of the same plant.
- **Example**: Maize is a well-known example of zetonogamy.

3. **Understanding Xenogamy**:
- Xenogamy is the transfer of pollen grains from the anther to the stigma of genetically different plants of the same species.
- This type of pollination promotes genetic diversity as it involves different genetic backgrounds.
- **Examples**: Plants such as squash, onion, and broccoli exhibit xenogamy.

4. **Analyzing the Options**:
- After reviewing the definitions and examples of autogamy, zetonogamy, and xenogamy, we find that all three types of pollination are correctly described in the options.
- Therefore, the conclusion is that all statements regarding the types of pollination are correct.

5. **Final Answer**:
- The correct option is **D**, which states that all of the above types of pollination (autogamy, zetonogamy, and xenogamy) are correct.