Answer : 3. "पिस्टिआ वाल्वॉक्स सर्पस हाइड्रिला – बलूत लैटाना "
Explanation :

Sequence of communities during hydrarch succession are as follows: Phytoplankton stage (Volvox) → submerged plant stage (Hydrilla) → submerged free floating plant stage (Pistia) →reed-swamp stage (Scirpus) → marsh-meadow stage (Lantana) → woodland stage → climax forest (Oak).