Understanding Placentation
Placentation refers to the arrangement of ovules within the ovary of a flower. It plays a crucial role in plant reproduction by determining how seeds develop from the fertilized ovules.

Types of Placentation
There are several types of placentation, including:
- **Free Central**: Ovules are attached to a central column of the ovary. Example: Dianthus.
- **Basal**: Ovules are attached at the base of the ovary. Example: Sunflower.
- **Axile**: Ovules are attached along the central axis of the ovary, usually with multiple locules. Example: Orange.
- **Parietal**: Ovules are attached to the inner wall of the ovary or its peripheral part. Example: Mustard.

Why Parietal is Correct
The correct option is **Parietal** because:
- **Attachment Location**: In parietal placentation, ovules are located along the walls of the ovary. This is significant for the development of seeds as they receive nutrients and support from the ovary wall.
- **Structural Characteristics**: Parietal placentation typically occurs in unilocular or multilocular ovaries, allowing for efficient seed development.
- **Botanical Examples**: Common examples of plants exhibiting parietal placentation include mustard and cucumbers, where the ovules are effectively positioned to optimize fertilization and seed maturation.

Conclusion
Understanding placentation helps in the study of plant reproductive structures, and recognizing parietal placentation as the correct answer reinforces knowledge of how ovules develop in specific arrangements within the ovary.