How can dna sequencing identify disease pathogens such as viruses?

Which would best keep the oxygen cycle stable? a. cutting down jungles to create farmland b. eliminating parks in large cities c. dumping toxic chemicals into the ocean d. reducing the amount of deforestation d. reducing the amount of deforestation

This is a biological reaction due to a stimulus. i need this quickly !

Where is most of the fresh water on earth found a in the ocean b in glaciers and in ice caps c in rivers d in the soil