One possible biosignature is considered to be the presence ozone.Why is ozone thought to indicate the presence of life?Select one:
A. Because it indicates the presence of oxygen in the atmosphere, which is an essential requirement for life.
B. Because it could support an alternate chemical basis for life that uses ozone in place of oxygen.
C. Because it means the planet has an ozone layer and therefore life would be protected from UV radiation from its star.
D. Because it indicates the presence of oxygen in the atmosphere, and we believe abundant oxygen can only be present if it continually produced by photosynthesis in organsisms such as green plants and cyanobacteria.