Other than poaching, what are the possible reasons for the decline in the population of Ganges River Dolphins? 1. Construction of dams and barrages on rivers 2. Increase in the population of crocodiles in rivers 3. Getting trapped in fishing nets accidentally 4. Use of synthetic fertilizers and other agricultural chemicals in crop-fields in the vicinity of rivers Select the correct answer using the code given below.

The Ganges River Dolphin (Platanista gangetica gangetica) is an endangered freshwater dolphin species. Besides poaching, several human-induced factors contribute to its decline:

1. Construction of dams and barrages on rivers: Dams and barrages fragment the dolphins' habitat, isolate populations, disrupt their migratory routes, and alter water flow and quality. This is a major threat. This statement is correct.

2. Increase in the population of crocodiles in rivers: While crocodiles are natural predators in riverine ecosystems, their population increase is generally not considered a primary or significant factor leading to the decline in Ganges River Dolphin numbers. The major threats are anthropogenic. This statement is incorrect as a primary reason for decline.

3. Getting trapped in fishing nets accidentally: This is a significant cause of mortality for Ganges River Dolphins. They often get entangled in fishing nets (especially gillnets) set by local fishermen, leading to drowning. This is known as bycatch. This statement is correct.

4. Use of synthetic fertilizers and other agricultural chemicals in crop-fields in the vicinity of rivers: Runoff from agricultural fields carries pesticides, herbicides, and excessive nutrients from fertilizers into the rivers. This chemical pollution degrades water quality, affects the dolphin's food chain, and can directly harm the dolphins. This statement is correct.

Therefore, factors 1, 3, and 4 are significant reasons for the decline in the Ganges River Dolphin population, in addition to poaching.