In Riccia, the female reproductive structures are called:

Options

A. Antheridium
B. Strobili
C. Archegonium
D. Oogonium

Answer

To answer the question "In Riccia, the female reproductive structures are called:", we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Organism**: Recognize that Riccia is a type of bryophyte, which is a group of non-vascular plants that includes liverworts and mosses.

2. **Understand Bryophyte Reproduction**: Bryophytes are known as "plant amphibians" because they require water for sexual reproduction. This is crucial for the fertilization process.

3. **Differentiate Between Male and Female Structures**: In bryophytes, there are two types of reproductive structures:
- **Male Reproductive Structure**: The male reproductive organ is called the **antheridium**, which produces sperm (antherozoids).
- **Female Reproductive Structure**: The female reproductive organ is called the **archegonium**, which produces egg cells.

4. **Analyze the Options**: Given the options:
- **Antheridium**: This is the male reproductive structure (incorrect).
- **Strobili**: This term refers to structures in conifers and is not applicable here (incorrect).
- **Archegonium**: This is the correct term for the female reproductive structure in Riccia (correct).
- **Oogonium**: This is a term used for female reproductive structures in certain algae and fungi, not in bryophytes (incorrect).

5. **Conclusion**: Based on the analysis, the correct answer is the **archegonium**.

### Final Answer:
The female reproductive structures in Riccia are called **archegonia**.