The correct option is (d).
Explanation
The delta regions of major rivers in India, such as the Ganga, Mahanadi, Krishna, Godavari, and Kaveri, support specialized vegetation known as Mangrove or Tidal forests. These ecosystems are characterized by mud and silt accumulation and are influenced by tides.
Analysis of Vegetation:
- The dense mangrove forests are the predominant vegetation in these areas, where the roots of the plants are submerged under water.
- The Sundari tree is a well-known species found in the Ganga-Brahmaputra delta, providing durable hard timber.
- In addition to the Sundari trees, other significant plant species found in these deltaic regions include Palm, Coconut, Keora, and Agar. These species are adapted to the specific soil and climatic conditions of the delta regions.
Conclusion:
Since Palm, Coconut, Keora, and Agar are all documented as growing in parts of these deltas alongside mangroves, all listed items are correct.
Key Takeaway:
The flora of Indian delta regions (Tidal Forests) extends beyond mangroves to include economically important species such as Sundari, Palm, Coconut, Keora, and Agar.