Pollen grains are produced in
(a) Anther
(b) Pollen sac
(c) Filament
(d) Stigma

Options

A. Anther
B. Pollen sac
C. Filament
D. Stigma.

Answer

To solve the question "Pollen grains are produced in," we need to analyze each option provided:

1. **Understanding Pollen Grains**:
- Pollen grains are haploid structures that carry male gametes. Their primary function is to transport these male gametes to the egg cell for fertilization.

2. **Analyzing the Options**:
- **(a) Anther**: The anther is part of the stamen and is responsible for the production of pollen grains through a process called microsporogenesis. This option is likely correct.
- **(b) Pollen sac**: Pollen sacs are structures within the anther where pollen grains are stored, not produced. Therefore, this option is incorrect.
- **(c) Filament**: The filament is a supporting structure of the stamen that holds the anther in place. It does not produce pollen grains, making this option incorrect.
- **(d) Stigma**: The stigma is part of the female reproductive structure of a flower and is where pollen grains land for fertilization. It does not produce pollen grains, so this option is also incorrect.

3. **Conclusion**:
- Based on the analysis, the correct answer is **(a) Anther**, as this is where pollen grains are produced.

### Final Answer:
Pollen grains are produced in **(a) Anther**.