Basal placentation occurs in

Options

A. Brassicaceae
B. Asteraceae
C. Poaceae
D. Both Poaceae and Asteraceae.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about basal placentation and which plant families exhibit this characteristic.

2. **Defining Basal Placentation**: Basal placentation is a type of placentation where the ovules are attached to the base of the ovary. This means that the ovules are positioned at the bottom of a unilocular ovary.

3. **Analyzing the Options**:
- **Option 1: Brassicaceae**: In this family, the type of placentation is parietal, where the ovules are attached to the walls of the ovary, not the base. Therefore, this option is incorrect.
- **Option 2: Asteraceae**: This family does exhibit basal placentation, where the ovules are attached at the base of the ovary. This option is correct.
- **Option 3: Poaceae**: Similar to Asteraceae, the Poaceae family also shows basal placentation. Thus, this option is also correct.
- **Option 4: Both Poaceae and Asteraceae**: Since both of these families exhibit basal placentation, this option is correct.

4. **Conclusion**: The correct answer is **Option 4: Both Poaceae and Asteraceae**.