*Q:10 Correct Answer* ✅ *(1) Both A and R are true and R is the correct explanation of A* > *Explanation:* Red algae (Rhodophyta) are commonly found in deeper parts of the ocean because they possess phycoerythrin pigment which efficiently absorb blue-green wavelengths of light. These wavelengths penetrate deeper into water, allowing red algae to perform photosynthesis even at considerable depths.