True sexual reproduction absent in :–

Options

A. Yellow green algae
B. Red algae
C. Green algae
D. Blue green algae

Answer

To solve the question "True sexual reproduction absent in:", we will analyze the options provided: Yellow green algae, Red algae, Green algae, and Blue green algae.

### Step-by-Step Solution:

1. **Understand the Types of Algae**:
- Algae are classified into different groups based on their pigmentation and other characteristics. The main groups mentioned in the question are Yellow green algae, Red algae, Green algae, and Blue green algae.

2. **Identify the Characteristics of Blue Green Algae**:
- Blue green algae, also known as cyanobacteria, are prokaryotic organisms. This means they lack a true nucleus and other membrane-bound organelles.

3. **Reproductive Methods in Blue Green Algae**:
- Blue green algae reproduce primarily through asexual methods such as binary fission and fragmentation. They do not undergo true sexual reproduction, which involves the fusion of gametes.

4. **Compare with Other Algae**:
- Yellow green algae, Red algae, and Green algae are eukaryotic organisms. These groups can exhibit sexual reproduction, involving meiosis and the formation of gametes.

5. **Conclusion**:
- Since Blue green algae are prokaryotic and do not engage in true sexual reproduction, the answer to the question is Blue green algae.

### Final Answer:
True sexual reproduction is absent in **Blue Green Algae**.

---