Sexual reproduction in Thallophyta takes place by :-

Options

A. Isogamy
B. Anisogamy
C. Oogamy
D. Any of the above

Answer

### Step-by-Step Solution:

1. **Understanding Thallophyta**:
- Thallophyta is a division of the plant kingdom that primarily includes algae. They are characterized by their simple structure, lacking differentiated organs such as stems, roots, and leaves. Additionally, they do not have vascular tissues.

2. **Types of Sexual Reproduction**:
- In Thallophyta, sexual reproduction can occur through three main types of gametic fusion:
- **Isogamy**: This involves the fusion of two gametes that are identical in size and shape. In this case, you cannot distinguish between the male and female gametes.
- **Anisogamy**: This involves the fusion of two gametes that are different in size and shape. Here, the male and female gametes can be differentiated.
- **Oogamy**: This type involves a large, non-motile female gamete and a smaller, motile male gamete. This is a more specialized form of reproduction.

3. **Examples of Algae**:
- The alga **Chlamydomonas** can reproduce through both isogamy and anisogamy.
- The alga **Volvox** reproduces through oogamy.

4. **Conclusion**:
- Since all three types of sexual reproduction (isogamy, anisogamy, and oogamy) are observed in Thallophyta, the answer to the question is that sexual reproduction in Thallophyta takes place by **any of the above**.