A researcher claims that the initial rise of oxygen in Earth’s early atmosphere, which occurred approximately 2.3 billion years ago, resulted from the metabolic activity of prokaryotic organisms. The claim is based on an interpretation of the geochemical and fossil evidence represented in Figure 1.
Which of the following types of evidence will best support the researcher’s claim?
a. Evidence that some of the earliest eukaryotes used oxygen to produce ATP by cellular respiration
b. Evidence that the earliest plants produced oxygen as a by-product of photosynthesis
c. Evidence that some of the earliest organisms carried out photosynthesis without producing oxygen
d. Evidence that the cyanobacteria produced oxygen as a by-product of photosynthesis