1 and 2 are correct.
The Wild Life Protection Act, 1972 is an Act of the Parliament of India enacted for protection of plants and animal species. The Act established schedules of protected plant and animal species. It has six schedules which give varying degrees of protection.
Schedule I and part II of Schedule II provide absolute protection – offences under these are prescribed the highest penalties.
Species listed in Schedule III and Schedule IV are also protected, but the penalties are much lower.
Schedule V includes the animals which may be hunted. They are known as Vermins.
Schedule VI is exclusive for Plants. The specified endemic plants in Schedule VI are prohibited from cultivation and planting.

All 1, 2 and 3 are correct.
An ice sheet is a mass of glacial land ice extending more than 50,000 square kilometers (20,000 square miles). The two ice sheets on Earth today cover most of Greenland and Antarctica. During the last ice age, ice sheets also covered much of North America and Scandinavia. Ice sheets contain enormous quantities of frozen water. Together, the Greenland and Antarctic Ice Sheets contain more than 99 percent of the freshwater ice on Earth.
Ice sheets form in areas where snow that falls in winter does not melt entirely over the summer. Over thousands of years, the layers of snow pile up into thick masses of ice, growing thicker and denser as the weight of new snow and ice layers compresses the older layers.
Ice sheets are constantly in motion, slowly flowing downhill under their own weight. The Greenland and Antarctic ice sheets also influence weather and climate

None of the above is correct.
Increasing anthropogenic activities along with natural stresses have led to massive degradation of one of India’s World Heritage Site — the Sunderbans.
Nutrient depletion especially phosphorus and nitrogen was found to be directly connected with the decline in forest cover.
There was a change in the species distribution — salt-sensitive ones such as Heriteira fomes, Xylocarpus species and Phoenix paludosa were not able to cope up with the increase in the salinity and declined while the tolerant varieties thrived.

3 and 4 are incorrect.
National Board for Wildlife:
• It is a “Statutory Organization” constituted under the Wildlife Protection Act, 1972.
• Its role is “advisory” in nature and advises the Central Government on framing policies and measures for conservation of wildlife in the country.
• Primary function of the Board is to promote the conservation and development of wildlife and forests.
• It has power to review all wildlife-related matters and approve projects in and around national parks and sanctuaries.
• No alternation of boundaries in national parks and wildlife sanctuaries can be done without approval of the NBWL.
• The NBWL is chaired by the Prime Minister.

The order can be logically arrived at by elimination.
Tropical rain forests receive overall more rainfall than seasonal forests and grasslands. So, (a) and (b) are eliminated.
Also, a forest will certainly be more productive than grassland. So, (c) is also eliminated. Correct answer will be (d).