In industry, microorganisms are often cultured in an environment where ideal conditions are maintained through continual nutrient provision and waste renewal. Such a system is called a .

Continuous Culture  

Explanation:

In industry, a continuous culture is maintained by providing the nutrient on time and removing the waste materials on time so that the optimum conditions inside the medium is maintained.

It is done to minimize the efforts which is required when the preparation is done to prepare the nutrient and inoculate the bacterial species.

Then by the time the bacterial species starts growing and then the useful product is extracted. In order to save the time and efforts the nutrient is supplied and waste materials is removed along with the useful products.

from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.    

b is the best answer for this question.