Why is the tundra treeless?
lack of sufficient water
permanently frozen ground
winters too harsh
too many fires

Option (2)

Explanation: Tundra region are those that are located at higher latitudes such as Canada, Greenland and the Alaska region, where the wind and vegetation is dry, slow  and the soils are covered with frozen ice, commonly known as the permafrost. This does not support the growth of plants and trees in this region as the sunlight is not sufficient and the whole year the temperature used to be cold because of its location at and around the Arctic circle.

Thus the correct answer is option (2).

answer: 20 percent

the fish culture has become a developing commercial practice in developing countries which is already prominent in developed countries of the world. the major fish protein demand is being supplemented in developing countries is   fishing to meet the needs of the growing population. therefore, in some developing nations, the percentage of animal protein from fish in the diet can be as high as 20 percent.

answer: b

coz red blood cells marrow and circulates the body for 120 days.