8. Which event was responsible for the increase in oxygen in the atmosphere during Precambrian time? (1 point)

a series of volcanic eruptions
the evolution of land animals
a comet crashing into the planet
the appearance of photosynthetic organisms

does anyone know the answers i have like 30 minutes

The event that was responsible for the increase in oxygen in the atmosphere during Precambrian time was the appearance of photosynthetic organisms.

To arrive at this answer, you can use your knowledge of Earth's history and the processes involved in oxygen production. The Precambrian period refers to the time before complex life forms evolved on Earth, and it is during this time that photosynthetic organisms first appeared.

Photosynthetic organisms, such as cyanobacteria, are capable of photosynthesis, a process through which they use sunlight to convert carbon dioxide and water into oxygen and glucose. These organisms were the first to introduce oxygen into the Earth's atmosphere through their metabolic activities.

On the other hand, while volcanic eruptions release gases into the atmosphere, including carbon dioxide, they do not directly contribute to an increase in oxygen levels. The evolution of land animals occurred much later, during the Paleozoic era, and while animals do play a role in the oxygen cycle, they were not responsible for the initial increase in atmospheric oxygen. The scenario of a comet crashing into the planet is unrelated to the increase in atmospheric oxygen during Precambrian time.

Therefore, the correct answer is the appearance of photosynthetic organisms.