What is the concept in which organismis need
other organisms in order to survive

This is known as interdependence. For example, living things that cannot make their own food must eat other organisms for food. Other interactions between living things include symbiotic relationships and competition for resources.

Explanation:

autosomal

explanation:

is a term used in genetic genealogy to describe dna which is inherited from the autosomal chromosomes

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.