Help will give 15 points In graph two, label A represents the gases hydrogen sulfide, methane, and carbon dioxide. What gases are represented by label B and how do these gas levels relate to the evolution of photosynthetic organisms?
Description of Graph:
The graph depicts the percentages of oxygen and carbon dioxide in Earth's atmosphere over time. The x-axis shows time in billions of years, and the y-axis shows percentages. Two curved lines depict the changing values of oxygen and carbon dioxide in the Earth's atmosphere over that time, but the lines are labeled with the variables "A" and "B."
The line labeled with the variable "A" depicts a substance with a percentage starting just above twenty five percent at 4.3 billion years ago. The percentage of this substance in the atmosphere decreases to about five percent by 4 billion years ago, and reaches a steady value of about one percent from 3.5 billion years ago to the end of the graph. The line depicting the second substance, labeled with the variable "B," appears around 2.3 billion years ago. It grows from zero to five percent by 2 billion years ago. The percentage of substance B in the atmosphere increases steadily, passing 20 percent by 1.5 billion years ago and leveling out at around 30 percent by 1 billion years ago.