Under which conditions are large numbers of fish in a lake most likely to die?

Look at the picture below . what does this picture represent ?

Microorganisms are involved in each of the following processes excepta. smog production. b. food production. c. infection. d. o2 production. e. decomposition of organic material.

What were the main components of earth’s earliest atmosphere? oxygen and ammonia hydrogen and helium oxygen and nitrogen hydrogen and nitrogen