Which element of the tundra ecosystem is biotic?

Biotic factors in the Arctic tundra, as with other ecosystems, include living organisms, such as microorganisms, plants and animals. The biotic factors of the tundra include over 1,500 species of plants, which classify as mosses, lichen and grasses. The hardy group of animals calling the tundra home includes many types of mammals and birds, including polar bears, Arctic foxes, caribou and other iconic species. 

Nimbostratus is the correct answer.
explanation: nimbostratus clouds are the type of clouds that are mostly likely present on gray, rainy day. these clouds produce continuous rain, snow and there is no thundering or lightening either.

True statement gravity force is more on bigger mass, less on smaller mass.all mass fall on planet with same acceleration and speeds