In rhodophyceae there is predominance of pigment r - phycoerythrin / phycocyanin.

Answer

**Step-by-Step Solution:**

1. **Identify the Group**: The question refers to the group Rhodophyceae, commonly known as red algae.

2. **Understand the Pigments**: The pigments mentioned are R-phycoerythrin and phycocyanin. It is important to know what these pigments are and where they are predominantly found.

3. **Function of Pigments**: Pigments play a crucial role in photosynthesis. They help in capturing light energy, which is essential for the process of photosynthesis.

4. **R-phycoerythrin**: This pigment is primarily responsible for the red coloration in red algae (Rhodophyceae). It is a type of phycobilin that absorbs light in the green and blue wavelengths, allowing red algae to perform photosynthesis efficiently in deeper waters where light is limited.

5. **Phycocyanin**: This pigment is associated with cyanobacteria (blue-green algae) and gives them a blue color. It contains copper, which contributes to its coloration. Phycocyanin is not found in Rhodophyceae.

6. **Conclusion**: Based on the information, R-phycoerythrin is the predominant pigment found in Rhodophyceae, while phycocyanin is found in cyanobacteria. Therefore, the correct answer to the question is R-phycoerythrin.

**Final Answer**: In Rhodophyceae, there is predominance of the pigment R-phycoerythrin.

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