At what levels do biologists study life???

Biologist study life to the extent to which they can uncover, unearth and investigate unseen, latent and concealed life forms that are still many in number, these crawling and under the water creatures. And in experimental sense, many biologists are guided by theethics in researching life forms. This is to protect and inhibit other biologist in killing thousands of these living organisms and prevent them from becoming extinct. Remember that biologists or any other scientists study because of knowledge and to contribute to the scientific world of making the ecosystem including us into a much better and cultured place and not the opposite. 

Hence, there are non-experimental and experimental approaches which are all subject to ethics. In exploring life forms, it is quite unlimited but studying life forms in experimental sense, it is somehow depends on the number of species that the biologists’ study.

Ibelieve the answer is c. 

Answer : romans built laws to manage the pollution which was lead by smoke produced by the factories.

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.