The endangered Ridley sea turtles have their worlds largest mass nesting aggregation at which of the following places?

Introduction / Context:
Olive Ridley sea turtles are an endangered marine species known for their spectacular mass nesting events, called arribadas, where thousands of females come ashore to lay eggs. Questions on environment and wildlife conservation often ask about important nesting sites for such species. This question tests your knowledge of the specific location where the worlds largest mass nesting aggregation of Olive Ridley turtles takes place. The correct site is Gahirmatha beach in Odisha, India, which is world famous for these large scale nesting events.

Given Data / Assumptions:

• The species in question is an endangered Ridley sea turtle, typically Olive Ridley turtles.
• The focus is on the worlds largest mass nesting aggregation site.
• Options include Gahirmatha, Sagarmatha, Lakshadweep Islands, Andaman and Nicobar Islands, and Gulf of Mannar.
• We assume familiarity with major Indian coastal and marine protected areas.

Concept / Approach:
Gahirmatha beach, located in the Kendrapara district of Odisha along the Bay of Bengal, is internationally recognized as the biggest arribada site for Olive Ridley turtles. Every year, during the nesting season, hundreds of thousands of turtles gather in the offshore waters and come ashore to lay eggs on the sandy beach. The other options are important ecological regions, but they are not known for hosting the worlds largest Olive Ridley nesting aggregation. Sagarmatha is a mountain national park in Nepal, and the islands mentioned have turtle nesting sites but not on the same massive scale as Gahirmatha.

Step-by-Step Solution:
Step 1: Identify that the question refers to endangered Ridley sea turtles, especially Olive Ridley turtles. Step 2: Recall that mass nesting sites for Olive Ridleys in India include Gahirmatha in Odisha, Rushikulya, and a few other beaches along the east coast. Step 3: Remember that Gahirmatha is widely described as the worlds largest mass nesting ground for these turtles. Step 4: Examine the options and match this description with Gahirmatha, Odisha. Step 5: Choose Gahirmatha, Odisha, as the correct answer.

Verification / Alternative check:
You can verify by recalling that environment and wildlife questions in many exams directly mention “Gahirmatha marine sanctuary” in Odisha as the largest rookery of Olive Ridley turtles. News reports on conservation efforts for these turtles often focus on this area during the nesting season. Sagarmatha National Park, by contrast, is located in the Himalayan region of Nepal and is associated with Mount Everest, not sea turtles. This contrast between a marine sanctuary on the Odisha coast and a high mountain park clearly supports Gahirmatha as the correct site.

Why Other Options Are Wrong:
Sagarmatha National Park: This is a mountain national park in Nepal and has no coastline; it is known for Everest and alpine ecosystems, not sea turtle nesting.
Lakshadweep Islands: These islands in the Arabian Sea have coral reefs and marine life, but they are not recognized as the worlds largest Olive Ridley nesting site.
Andaman and Nicobar Islands: These islands in the Bay of Bengal also have turtle nesting beaches, but the biggest mass aggregations occur at Gahirmatha.
Gulf of Mannar: This gulf between India and Sri Lanka is a marine biodiversity hotspot but is not the primary arribada site for Olive Ridley turtles.

Common Pitfalls:
A frequent mistake is to assume that any island or marine region listed in the options could be the correct answer and to guess randomly. Another pitfall is confusing Sagarmatha with Gahirmatha because the names sound somewhat similar, even though one is a mountain park and the other is a coastal sanctuary. To avoid such confusion, remember a simple association: Gahirmatha and G for great gatherings of Olive Ridley turtles. This memory aid highlights that Gahirmatha in Odisha is the key nesting site mentioned in conservation discussions.

Final Answer:
The worlds largest mass nesting aggregation of endangered Ridley sea turtles occurs at Gahirmatha, Odisha.