2 and 3 are correct.
BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats.
BirdLife International’s priorities include preventing extinction of bird species, identifying and safeguarding important sites for birds, maintaining and restoring key bird habitats, and empowering conservationists worldwide.
BirdLife International has identified 13,000 Important Bird and Biodiversity Areas and is the official International Union for Conservation of Nature’s Red List authority for birds.
As of 2015, BirdLife International has established that 1,375 bird species (13% of the total) are threatened with extinction (critically endangered, endangered or vulnerable). BirdLife International publishes a quarterly magazine, BirdLife: The Magazine, which contains recent news and authoritative articles about birds and their conservation.

Only 2 is correct.
Hard bottom communities like corals and mussel banks (including oysters) are more sensitive to siltation. Siltation adversely affects coral population.
In rural areas the erosion source is typically soil degradation due to intensive or inadequate agricultural practices, leading to soil erosion, especially in fine-grained soils such as loess. The result will be an increased amount of silt and clay in the water bodies that drain the area often adding unwanted fertilizers to these bodies.

1, 2 and 3 are correct.
Light pollution is excessive brightness that causes visual discomfort.
• Skyglow is the brightening of the night sky over inhabited areas. It is caused by cluttered, bright, excessive and confusing groupings of light sources.
• It affects the reproductive cycles of those animals that depend on sensing light movements or seasonal movements to reproduce. Since birds migrate using star light, it can confuse them, and even disorient night-flying insects.
• Excessive blue light emitted from LEDs directly affects sleep pattern in Human by suppressing the production of the hormone melatonin, which mediates the sleep-wake cycle in humans.

1 and 2 are correct.
Biodiversity loss describes the decline in the number, genetic variability, and variety of species, and the biological communities in a given area. This loss in the variety of life can lead to a breakdown in the functioning of the ecosystem where decline has happened.
An area’s biodiversity increases and decreases with natural cycles. Seasonal changes, such as the onset of spring, create opportunities for feeding and breeding, increasing biodiversity as the populations of many species rise. In contrast, the onset of winter temporarily decreases an area’s biodiversity, as warm-adapted insects die and migrating animals leave. In addition, the seasonal rise and fall of plant and invertebrate populations (such as insects and plankton), which serve as food for other forms of life, also determine an area’s biodiversity.

None of the above is incorrect.
Fly ash, the end product of combustion during the process of power generation in the coal based thermal power plants, is a proven resource material for many applications of construction industries and currently is being utilized in manufacturing of Portland Cement, bricks/blocks/tiles manufacturing, road embankment construction and low-lying area development, etc.
Fly ash contains heavy metals from coal, a large amount of PM 2.5 and black carbon (BC).
Fly ash, in view of its alkalinity and water absorption capacity, may be used in combination with other alkaline materials to transform sewage sludge into organic fertilizer or biofuel.