In algae we find -

Options

A. Isogamy
B. Anisogamy
C. Oogamy
D. All

Answer

### Step-by-Step Solution:

1. **Understanding Algae**: Algae are simple, chlorophyll-bearing, thalloid, autotrophic organisms that are primarily aquatic. This means they can photosynthesize and are mostly found in water bodies.

2. **Reproductive Methods in Algae**: Algae reproduce through three main methods: vegetative, asexual, and sexual reproduction. In this context, we will focus on sexual reproduction.

3. **Types of Sexual Reproduction**:
- **Isogamy**: This type involves the fusion of two gametes that are similar in size and shape. An example of isogamy in algae is found in the genus Spirogyra, where the gametes are of the same size and flagellated.
- **Anisogamy**: In this type, the gametes are dissimilar in size. One gamete is larger, while the other is smaller. This type of reproduction also occurs in some algae.
- **Oogamy**: This is characterized by the presence of one large, non-motile gamete (egg) and one smaller, motile gamete (sperm). This type of reproduction is also observed in certain algae.

4. **Conclusion**: Based on the types of sexual reproduction found in algae, we can conclude that algae exhibit isogamy, anisogamy, and oogamy. Therefore, the correct answer to the question "In algae we find" is all three types of sexual reproduction.