The saltwater mangrove swamp that forms in the lower part of the Ganges delta is called the Sundarbans. The name comes from the abundance of which type of mangrove tree in that region?

Introduction / Context:
The Sundarbans is a famous mangrove region located in the lower part of the Ganges delta, spread across India and Bangladesh. It is known for its unique ecosystem and for being the home of the Royal Bengal Tiger. The name Sundarbans itself has an interesting origin linked to a particular species of mangrove tree. This question checks whether you know that Sundarbans derives its name from the Sundari mangrove tree, which grows abundantly in the area.

Given Data / Assumptions:

• The swamp is the Sundarbans in the Ganges delta.
• The question asks about the specific mangrove tree that gives the region its name.
• Four types of mangrove trees or related species are given as options.
• We rely on standard geography and environment references.

Concept / Approach:
In Bengali and related languages, Sundar can mean beautiful, and Sundari refers to a particular mangrove species, Heritiera fomes. Many sources explain that the name Sundarbans is linked to the abundance of Sundari trees in the mangrove forests. While the exact linguistic origin may include more than one interpretation, school and competitive exam texts consistently state that Sundarbans is named after the Sundari mangrove tree. Other mangrove genera like Rhizophora and Avicennia are present in the region but do not form the basis of the common name.

Step-by-Step Solution:
Step 1: Identify that the region in question is the Sundarbans mangrove forest. Step 2: Recall that the name Sundarbans is commonly linked to the Sundari tree species. Step 3: Look for the option that clearly mentions the Sundari mangrove tree. Step 4: Confirm that Rhizophora, Avicennia, and mangrove date palm are generic or other species without name based association. Step 5: Select Sundari mangrove tree as the correct answer.

Verification / Alternative check:
Environmental studies and geography textbooks describing Indian biosphere reserves and national parks often include a note explaining the origin of the name Sundarbans. They state that the name is derived from the Sundari tree, which dominates the mangrove vegetation in many parts of the region. Conservation related documents and tourist information material also repeat this explanation. While scientific research discusses multiple mangrove species in the area, the exam oriented explanation consistently highlights the Sundari tree as the source of the name.

Why Other Options Are Wrong:
Rhizophora mangrove: A genus of mangroves that includes species like red mangrove, present in many coastal wetlands, but not directly linked to the region's name.

Avicennia mangrove: Includes species such as Avicennia marina, also present in mangrove ecosystems, but not used to derive the Sundarbans name.

Mangrove date palm: A descriptive term that does not match the well known Sundari species and is not used in standard explanations of the name.

Common Pitfalls:
A candidate unfamiliar with mangrove species names may quickly guess any scientific sounding option such as Rhizophora or Avicennia. Others may rely only on the translation of Sundarbans as beautiful forest and forget the botanic link. To avoid such mistakes, remember that almost every competitive exam book connects Sundarbans with the Sundari tree. Making a small list of biosphere reserves and the species they are named after, such as Sundari for Sundarbans, helps retain this information for exams.

Final Answer:
The Sundarbans gets its name from the abundance of the Sundari mangrove tree in the region.