An evergreen forest is a forest consisting entirely or mainly of evergreen trees that retain green foliage all year round. Such forests reign in the equatorial region, between the tropics primarily as broadleaf evergreens, and in temperate and boreal latitudes primarily as coniferous evergreens.

Correct Option: D

An evergreen forest is a forest consisting entirely or mainly of evergreen trees that retain green foliage all year round. Such forests reign in the equatorial region, between the tropics primarily as broadleaf evergreens, and in temperate and boreal latitudes primarily as coniferous evergreens.

Productivity is the rate of organic matter or biomass production. The average ocean productivity is about 50 grams carbon per square meter per year; while, the average land productivity is 160 grams carbon per square meter per year. Salt marshes and mangroves have one of the highest productivity of 3300-6000 grams carbon per square meter per year. So the correct sequence of ecosystem in the order decreasing productivity is: Mangroves > Grasslands > Lakes > Oceans.

Correct Option: D

Productivity is the rate of organic matter or biomass production. The average ocean productivity is about 50 grams carbon per square meter per year; while, the average land productivity is 160 grams carbon per square meter per year. Salt marshes and mangroves have one of the highest productivity of 3300-6000 grams carbon per square meter per year. So the correct sequence of ecosystem in the order decreasing productivity is: Mangroves > Grasslands > Lakes > Oceans.

Some of the natural sources of air pollution are ground dust, salt spray from oceans, volcanic eruptions, hydrogen sulfides from natural sources, etc. Large amount of gases and ash from volcanic eruptions blacken the skies and increase the background pollution levels for years.

Correct Option: B

Some of the natural sources of air pollution are ground dust, salt spray from oceans, volcanic eruptions, hydrogen sulfides from natural sources, etc. Large amount of gases and ash from volcanic eruptions blacken the skies and increase the background pollution levels for years.

Tropical rainforests exhibit high levels of biodiversity. Around 40% to 75% of all biotic species are indigenous to the rainforests.[6] Rainforests are home to half of all the living animal and plant species on the planet. Two-thirds of all flowering plants can be found in rainforests.

Correct Option: C

Tropical rainforests exhibit high levels of biodiversity. Around 40% to 75% of all biotic species are indigenous to the rainforests.[6] Rainforests are home to half of all the living animal and plant species on the planet. Two-thirds of all flowering plants can be found in rainforests.

The Steppe is a dry, cold, grassland that is found in all of the continents except Australia and Antarctica. It is mostly found in the USA, Mongolia, Siberia, Tibet and China. is usually found between the desert and the forest.

Correct Option: A

The Steppe is a dry, cold, grassland that is found in all of the continents except Australia and Antarctica. It is mostly found in the USA, Mongolia, Siberia, Tibet and China. is usually found between the desert and the forest.